Anyone recognise this Sprite door lock?

I don't but I had a similar problem with a heavy outside padlock that wouldn't let the key go in after the winter, a few squirts of WD40 where ever I could squirt it outside and into the key hole over a few days cured it, it might be worth a go?

Otherwise a locksmith might help?

Try looking on YouTube or a local mobile caravan service engineer? 

Update: Having looked at replacement lock kits on various web sites it's fairly clear that the central disc is levered off. Then having watched a this Youtube video (https://www.youtube.com/watch?v=zxlFix_qmHg&t=432s) it semed worth having a go. So went out full of confidence with toolbox and lo and behold the key worked and the lock worked. No idea what had changed, it was certainly not working. I can only assume the lock fairy has been around. So I gave it a good dose of lock lubricant and all seems fine.

So it seems all you have to do is let the lock fairy do her magic. Thought I'd pass on that bit of information.

That’s a Hartal Evoline door lock. A Google search should provide further information. Good luck!