Sliding door problems

[montypsx]

Hi all. I've got a problem with my sliding door, it locks and unlocks, handles work perfectly inside and out. The problem is that the door releases and the rear of the door comes out but then the door won't slide back. Any ideas please on how I can get it open so I can fix it and what's wrong with it. Forgot to mention there's no drop or play in the door hinges so that's not the problem
Regards Phil

 

[21Window]

Is the plastic/nylon cam still in place? The square shaped piece which sits on the rail fitted to the middle hinge?

 

[montypsx]

Yes pal it is, it feels like the hook latch thingy bit in the handle won't lift up so the door can side open if that makes any sense