if its the UV tube bulb, take it back and make them replace it. your supposed to replace them every 6mo-year. they will still work after that for a very long time(they just don't put out UVB any longer). I've never actually seen one that quit working before it hit the UVB expiration.
If its the little basking bulb, I'd say your lucky it lasted that long...they're crap. don't waste your money, buy a regular house bulb(40 or 60 watt)