take panel or glass out,then force the door towards hinge side and should open,then check if theres a small screw holding latch to the lockstrip and tighten if it is loose,,if not or it hasnt got one you will have to buy a replacement lockstrip if you want this function to work,if not take the latch keep off the frame,but if you do this you will have to lift handle up to keep door closed,hope this helps
shaun www.sdwupvcrepair.co.uk, February 2009