My Freezer will not freeze how can I fix my Teka model TGI120.1D?

My teka inbuilt upright freezer unit TGI 120.1D no longer freezes indeed it does not get cold this happened after we experienced a power failure.I have power to the freezer as all the lights come on and the alarm works.
I have noted that the large black compressor at the back of the freezer gets very hot is this normal other than this problem the freezer is in very good conditionand although 3 years old is very little used except fot the past 12 months