Step 1 With door in open position, knock a wedge underneath the latch side to support its weight. Unscrew hinges and lift door out.
Step 2 Drill out holes where screws won’t grip using 5mm bit. Using a bit that is a millimetre smaller than the dowel will make it a tight fit. If the back of the door jamb is visible, as it is here, wrap a piece of tape around drill bit as a depth-guide so you don’t drill too deep.
STEP 3 Squeeze PVA glue into holes and tap in a short length of dowel. Using sharp chisel, cut off dowel so it’s flush with the hinge housing. Leave to dry.
STEP 4 Wedge door up in open position. First screw hinges into holes that didn’t need repairing.Drill pilot holes into dowel using hinge as a guide, then screw on.