How can i fix my Bauknecht KGNA305/WH frost free fridge freezer?

My fridge freezer has stopped working all of a sudden. When its plugged in it makes all the right sort of sounds as if it was all working fine, when the fridge door is opened the light comes on but its not cold at all and the freezer compartment is colder than the fridge but not cold enough to even freeze water in the ice cube tray. I've had the cover off the electrics at the bottom rear of the freezer and all seems to be in order. The compressor is working as its getting hot but i think maybe too hot as i have compared it to my stand alone freezer which i'm able to keep my hand on but my fridge freezer compressor is roasting. There didnt seem to be any degredation in temperature it was just really quite sudden. Could you give me any advice as to the possible problem as i dont want to bin it for something really simple.