what is it i need to buy? or what could it be?

try checking your fuses. sounds like a blown fuse or two.

the Eric guy is correct check your fuses but you need to consult your owner's manual to make sure that the fuses are in the correct slots make sure they have the right amp fuse there should not be a 10 amp fuse in a 7.5 spot or 15 amp spot this will cause any car to not start or work properly and many fuses blowing I have had this problem once with my 02 Lancer ES 5 speed this was the result I had once one fuse blew and as I replace the fuse it blew again turns out fuses were not where they supposed to sew power is not evenly flowing through the car which results in the engine stalling at times or just cutting off as if the battery was bad or the alternator was bad and it will be a fuse all alone so make sure you have the owner's manual which shows you a diagram of the fuse boxes under the hood and the one under the steering wheel with the proper fuse amp I just did this for a Camry that is badly used and third person owner car ran fine the whole time he has had it and then it just stopped at AutoZone when he when to start the car it wouldn't start so battery was tested starter was tested starter switch test out fine so I came across a fuse box with fuses switched around when straightened out in 5 minutes car is running better than it was when it was new seriously