A model number may help others help you.

Check to see if the compressor is running.
You usually can hear it also you should be able to feel it vibrating and it should be warm.

If it is running then it is time to get a new unit as fixing it will cost more than it is worth.

If it has an interior light, does it work?
Is it making any noise re: clicking as the compressor tries to start?

mnagode

I do not have info on the unit but it sounds like a simple fridge setup.

You could check to see if the compressor is getting power (120volts AC).

If not you probably have a thermostat problem.
Unplug the unit and measure across the thermostat contacts, should be 0 ohms.
Be sure to detach at least one wire to the thermostat. This prevents you from reading an alternate/parallel circuit path.

If you do not have a meter you could do the following jiggery pokery.
Unplug the unit.
If the thermostat has just 2 contacts, remove them from the thermostat.
Short them together.
Tape them up so they cannot short to anything else.
Plug the unit in.
If it fires up then your thermostat is shot.

If it is getting power then the following should help checking other components.

Here are a couple good links.
http://www.applianceaid.com/frig.html
Refrigerator Repair Guide: How To Fix a Refrigerator - ACME HOW TO.com

If you do not own a meter, I would suggest you purchase a one. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.

There is a good STICKY at the start of this forum about it's use.

Not familiar with this unit but with luck it is a standard type of system.

Remove the freezer cover so you can see the evaporator coils.

If they are heavily iced/frosted over you have a defrost problem.

If there is no frost or only frost in one area then you have a compressor problem or are out of freon or are low on freon.
All of these will be expensive repairs so usually it makes more sense to invest those dollars in a new unit.