Is the compressor at the back running?
Is it hot to touch?
The compressor is the black pot on the back at the bottom.
Ok sorry not good news im afraid.
If the compressor is hot but the fridge and freezer isnt running then the compressor is the problem. As sometimes they can jam up and stops working but the compressor will get hot as it carnt run.
So im afraid the cure for this is to repalce it. But this isnt going to be cheap. As a new compressor you will be looking at about the £200 mark. So given the price it will be better to replace the fridge then actually repaire it.
Sorry this isnt good news.