Can you help with an interior door handle issue?

We have a plywood interior door (to the washing machine cupboard), the handle was screwed in originally from the back and has a catch but it's all broken and we want to replace the broken handle with one you just screw in and doesn't move. However we can't get the catch mechanism out and the door is crumbling around where the original handle is. We either want someone to replace the door handle or replace the door - but it seems to be a non standard size. Can you help?