Hiya,
This is failry old appliance I think as there's no date code for it on the service discs.
I'm assuming it's now on at the wall or remote switch, ensure that the thermostat is on too. This is located near the lights, normally a small rotary dial and numbered. The mid number is the normal setting.
If everything is on you need to check that the compressor is running. Unfortunately this is at the rear of the appliance and would mean that you have to take the appliance out from it's built in position.
Check that the compressor is running. If it is, is it very hot?
If it is running and there's no cooling it would suggest either a faulty compressor or a lack / leak of the refrigerant gas. This would require a refrigeration engineer to attend and possibly replace the compressor and regas the appliance. This would be a fairly expensive repair.
If it's not running then it could be as simple as a faulty thermostat.
Hope this is of some help.
Let me know how it goes or if you need more help.
Thanks
Home Appliance Technician
Whitegoods engineer working for a multibranded national company in the UK.