Broken star lock

Norman_Castle

the key goes in and just turns and turns, there are no 'teeth' to grip it on the inside and it feels like there is nothing in there to grip it anymore.

Get a torch and look inside it. If the serrated edge has stripped it should only be in one small place. Try hooking the remaining teeth with a bent nail. Was the lock difficult to open? If so try moving the door in various directions to make it easier.
Some shed door hinges can be unscrewed, is this an option?
Are the tools you need to get into the shed, in the shed?

-taff

There are no serrated edges in there, the hole in the front of the door is the size of the key so a torch doesn't show me much ( I took the hole cover off with a kitchen knife ) the door was installed by my father to open inwards so the hinges are inside. It's an old wooden front door so it's solid.
When my father installed anything, there were never shortcuts in the unhappy event of failure down the line.
My tools are where I live usually, the shed is in Wales ( yes, the tools there are in the shed) so I need to be prepared for when I go back sunday.
Thank you for the suggestions, I'll get tooled up this weekend and report any success.

southcoastrgi

I'd go to one of the sheds & buy a new key 1st yours wouldn't be the first one that's worn

-taff

Had to remove the wood in front of the barrel above and below it and chisel out a bit more towards the front of the lock because there were two screws holding the faceplate in.
Success though. Yay.
The rack had snapped, key was fine.
Will have to replace at a later date.
Thanks all.