I have a mountfield 480t that worked yesterday but won't start this mornining I put it in the shed lat night at an angle two back wheels of the floor could this have caused a problem

Hi,
Difficult to be sure, but if that angle in some way affected the carb, fuel level, float operation, etc. you could have gotten fuel where it does not belong in sufficient quantities to soak the air filter or simply flood the engine.
I would disassemble a bit and look for the presence of excess (puddling) of fuel in the intake tract.
Peace,
Clarke