You'll need to buy a new door, the same size as the old door and a doorknob drill kit both of which you can get at your local home improvement center.
Pull the hinge pins and removing the old door and align the top and sides.
Clamp doors together and transfer the placement for the hinge and latch plate with a framing square. You can also trace the existing door knob hole as well as the length if the old door is shorter than the new one. Unclamp the doors.
Use doorknob kit to drill the knob and latch holes. When you're working on the hole for the doorknob, drill through the front of the door until the guide bit breaks through the back side. Then, flip the door over and finish drilling from the other side. this will prevent the wood from splintering around hole.
Also, be aware the hole saw will get extremely hot while you're working with it. You should pull on some gloves so you don't burn yourself when you're removing the bit.
Align the hinge plate template to the side of the door and transfer the use a chisel to carve out the latch plate and the hinges.
If you're new door is shorter than the old one you will also need to cut the bottom edge of the door. run a piece of tape along the line to prevent splintering.
Screw the hinges into the new door replace the hinge pins and then install the door knob and make sure door closes correctly. I'm Mrs. Fixit and it's just that simple!
