This is a simple task that takes less than an hour with a few right tools.
When a door handle or door lock breaks or comes loose in your house, you may need to remove it from the door. Once the old lock is off, it's relatively easy to install a new one. You will need the below tools to get started.
Adjustable pliers.
Allen wrench.
Screwdriver.
Drill.
First, you need to remove the visible screws that attach the bevelled side of the door handle to the door jam with an adjustable Allen wrench or pliers. Here's a tip: Any small screw, small pin or hex head screw can easily be pulled out using a narrow screwdriver. The right tools will make your life easier. Feel free to ask your local supplier which tool kit is most appropriate. Make sure to find support for the door before you loosen any mounting screws. If it's stubborn, spray on some lubricant before trying again. You don't want your landlord calling because you damaged the door while you unscrew it.
Pull out the screws from the door handle itself. You'll need a drill to take these out, or a screwdriver if you have a manual drill. These are usually located on the inside surface of the door so the screw head is not visible at first glance. When all four exposed screws have been removed, pry off the old handle with a small flat head screwdriver or wrench. It should come right off. Set it aside as well for now.
If your new handle requires assembly before installation, this is the time to do it. Most modern handles don't require assembly though...they just clip in place! So let's move forward assuming that yours doesn't need any additional assembly. Once you've opened up the package you should see two pieces. One is the handle itself, and the other is a plate that will cover any rough edges to protect your door (and your hands/feet!) When you've taken both pieces out, take note if there is any small hole or notch on the face of the new handle that isn't present on the old one. If there is a hole, make sure this area lines up with corresponding the hole or notch in the door to ensure proper placement.
Line up all four screw holes to match those in the door jambs, and slide them through. It's always best to check again for assembly by popping open the packaging just in case! The long part of each hole needs to line up with where the door jam is. If you've assembled the handle to the plate, just line the holes up instead and check for any movement. The handle should not move at all once it's in place! If it moves out of position you need to redo this step, otherwise push screws into each hole and turn them lightly with your hand or a screwdriver until they snuggle right down snug against the plate. It may take a while so be patient here. Don't crank down too hard.
Many modern door knob designs have hidden screws that are not visible. You can pop the handle off by using a flat head screwdriver or flat bar to pry the interior side of the latch assembly, which will pop out of place. Sometimes you may need to knock out any remaining bits of metal holding it in place depending on the length of the doorknob shaft with a hammer and chisel before reinstalling your new handle. Sometimes there are no visible holes for screws on either side of the internal mechanism - this means that there is likely an additional support plate behind the casing. Pry it off (gently) to reveal more hidden screws underneath. If you see a screw head, it means you have exposed the hidden screws. Remove the exposed screws and proceed as normal.
One side of the door will have a little interior knob; this is called the "lever". The other side will be blocked by the door stop, so you need to clear it out of the way. Use your chisel and hammer to pull the remaining bits of metal from inside the door jam. Once done, insert your flat head screwdriver into any visible gaps in the knob and pop the door open. Then, unscrew any screws holding the handle in place and put it away for now. There may be a few screws in different locations, so make sure you keep track of which ones go where when you unscrew them. Now that the door is open, flip it over and simply unscrew any visible screws from the backside of the handle. Slide it out and put away for now. If your new lever handle doesn't already come with a cover plate to cover any part of the door edge which is rough, use some pliers to bend up a piece of sheet metal into place before installing the new handle using screws from inside. Always test your handle before closing up.
With door knobs that have privacy locks, there are usually screws in opposite directions of the mechanism. These may be covered by a cover plate, so check behind it before you unscrew your handle with your Philips head screwdriver. After removing these screws you should be able to pull out the door handle and put it away for later installation. Once done, use your chisel to knock out any remaining bits of metal from inside the door jam. Then install using your screws. If you still cannot find the screws after checking both sides of your internal mechanism, you will need to knock out all metal parts until they are separated enough that you can pry them apart with a flathead screwdriver. You may also need to finish it off with a chisel and hammer. You should still be able to use the same holes from before, so keep track of your screws. Reinstall with your new handle once you're done.
Most doors (with or without a spindle) have locks that become harder to open as they get older, so if you are seeing any rust or other buildup around the inside of your door lock, you can use a cotton swab with some isopropyl alcohol to clean it off. Many newer handle locks have screws hidden behind a latch plate - look for any metal hiding spots on either side of your latch plate. If there are none, then you will need to gently pry the centre out using a flat bar or screwdriver before removing all of the parts that remain in place. Once enough room is made between each part, you should be able to knock them apart with a chisel and hammer until they come loose enough that you can slide them apart by hand. Once they are pried apart, simply remove the exposed screws from the latch plate and pull it out. You will likely need to use a flat head screwdriver to pop off any bits of metal from inside the door jam as well. Then install your new handle lock using those same holes - but make sure you test first! For better security, you can install a strike plate. A strike plate will hold up against forced entry. So, you can be safe in your beds after locking your self-built security systems.
If you are looking at the back of the doorknob and cannot find any visible screws, you will need to tap it loose with your hammer before you can remove a door knob or its mounting screws. Tap around the edges until it comes off, then unscrew your latch plate using your screwdriver or chisel if necessary.
Installing or removing a doorknob is simple - just use your old round cover plate or install one that comes with your new handle if needed, then slide the latch mechanism straight in where you removed the old one. Once installed, remember to reopen and test before closing.Many newer door handles can be done using one of the methods above, while others may need more work. Using your screwdriver and chisel, start at the edges to remove all metal parts from inside the door jam until they are pried apart enough that you can pull them out by hand. Remove any screw connecting pieces before pulling out each part completely. Once this is down, install with your new handle using the same holes if possible. If not, use your flat head screwdriver to carefully pry open or even knock out bits of metal before installing it in place. After installation, remember to test and reopen before closing! Some older doorknobs have visible screws on either side of the door - these will be hidden behind a small cover plate on either side of your door lock. Use the same screwdriver and chisel techniques to knock out any metal bits before removing each part that remains in place. You may also need to use a flat head screwdriver in order to pop apart some parts if they are stuck together too hard. Once pried apart, remove screws from the latch plate and free it from the door jam using a flat head screw driver if necessary. Then install your new handle with those same holes, remembering to test it first! If you cannot find screws on either side of your doorknob then you will have to tap all screws loose with a hammer before removing the pieces by hand. Free them from the door jam using a flat bar or screwdriver as needed before replacing them with your new doorknob. If you are swapping out an old doorknob for a new one, then you will need to remove the latch mechanism first using your screwdriver or chisel if necessary. Then install it back in place.
Door handles are attached to the door either by screws or latch bolts. If the handle is hanging on by a screw, usually all you need to do is remove the screw, replace it with a longer one and tighten it or use two screws. In most cases, the handle will come right off. If this doesn't work try removing the screw altogether and force some WD-40 into the hole while trying to twist off. There should be a rubber gasket that you can leave out while using WD-40. If there isn't a rubber gasket use some plumber's grease instead of WD-40 since it's thicker and won't run as easily. If you have a latch bolt holding your handle on this solution may not so well because bolts probably go through the handle and into the door on either side of it. With a latch bolt there is usually more room to work with, so try using longer bolts only after you measure the hole. If this doesn't work you may need to drill through the slot in your door or pull out your inner layer of drywall if you have one of those doors with layers.
You might have a door handle or door lock that needs to be taken off by removing the bolt holding it on. This particular bolt is located behind the doorknob, so grab your screwdriver and take that baby out. It may take some elbow grease but keep twisting until you feel that satisfying "click". The only thing left to do then would be to take off the handle itself by twisting counterclockwise (to your right).
Now take your replacement handle and line up each small slot. Don't forget about those little metal things called "spacers", because if you don't insert them back where they belong (i.e. between the inner side of the small hole and the bottom of your new lever) you won't be able to screw the bolt back on. Just line everything up, insert your bolt and tighten it down with recessed fasteners and screw it either your screwdriver or an Allen wrench. Congrats! You're now the proud owner of that snazzy new lever door handle. locks are an integral part of home safety, according to the Australian Government's Your Home website.