Diagnose why a door won't latch, fix loose hinges, then realign or deepen the strike plate to fix it.
DL-01Work out why the latch isn't catchingClose the door slowly and watch exactly where it sticks. Look for a gap between the door and frame that's bigger at the top or bottom — that means the door has dropped. Check if the latch tongue is missing the strike plate hole completely, catching on the edge, or reaching the hole but not clicking in.
DL-02Check and tighten the hinge screwsOpen the door and tighten every hinge screw with a screwdriver, top hinge first. Loose hinges are the most common reason a door drops and stops latching. If a screw spins without tightening, the hole is stripped — go to the next step before doing anything else.
DL-03Repair a stripped hinge screw holeRemove the loose screw. Dip a few cocktail sticks or matchsticks in PVA glue, push them into the hole until it's tightly packed, then snap them flush. Let the glue go off for at least 20 minutes, then re-drive the original screw — it will bite properly again.
DL-04Check the strike plate alignmentShut the door gently and mark on the frame exactly where the latch tongue is hitting, using a pencil. Compare this to the centre of the strike plate hole. Small misalignments of a few mm are common and easy to fix without moving the whole plate.
DL-05Adjust the strike plate positionUnscrew the strike plate. If it only needs to move a few mm, fill the old screw holes with wood filler, let it dry, then reposition the plate and drill new 2mm pilot holes before refitting. Slightly enlarging the hole in the plate itself with a fine file can also help if the latch is only just missing.
DL-06Deepen the mortise if the latch still won't reachIf the door has dropped and the latch tongue no longer reaches the hole at all, the mortise behind the strike plate needs to go deeper. Score the new line with a chisel, tap it in gently to remove thin slices of timber, and check the fit often rather than removing too much at once.
DL-07Refit the strike plate and screw it homeSit the plate back in its recess, check it sits flush with the frame, and drive the screws in fully. Use slightly longer screws (40mm) if the originals are stripped or too short to bite into solid timber behind the frame lining.
DL-08Lubricate, test, and tidy upSpray a little graphite or dry lubricant into the latch mechanism itself, not oil, which attracts dust. Open and shut the door ten or so times to check it latches smoothly from every angle. Sweep up any wood shavings or filler dust and wipe the frame clean.