Adjusting a door latch
If a door will not close properly, the first place to look is the strike plate on the door jamb. Take a screwdriver and tighten the screws, making sure that these are the proper 1" screws. If the screws do not tighten, insert a toothpick in the hole and break it off at the jamb. Repeat until the hole is plugged. The screw will penetrate the cluster of toothpicks and form a tight bond. When the door is closed, if the strike plate does not match up, tighten the hinge screws and use the toothpick method to ensure a tight fit.
Tip: if the latch does not match with the strike plate, colour the door bolt with a felt pen and close again. The pen mark will show the position of the door bolt. The strike plate may have to be lowered and this means taking it off and either filing a bigger hole or chiseling out an extension to the mortise on the jamb, either higher or lower than the strike plate. When this is done, re-attach the strike plate.