freezer failure?

My Zanussi model ZFU 325W upright freezer (located in the garage) has recently failed and I have had to throw out quite a lot of food.

It has a climate rating of "N" so I appreciate that in winter there could be problems as the ambient temperature might be too cold. However, it has failed in August when this is not a problem!

I'm told that it might need a "regas" (whatever that is!) - which couldbe an economical repair - or that the compressor has failed (why?) - which is unlikely to be an economical repair.

The freezer is only 2 years old and I don't want to have to buy a new one if this can be avoided.

Any suggestions as to what might be wrong and why?