My car has been sitting for about 3 weeks and won't start now, had barely any gas so i went and put some in, still didn't start, i don't think it's the battery because all the electric stuff works, it started for like 3 seconds then died out, and now it won't even turn over, it sounds like it wants to but doesn't even with gas in it, could it be lack of oil?, theres little in it right now

 

also it's been pretty cold out i dont know if that would have anything to do with it, having my car sit that long would it damage anything besides the battery?

 

It sounds like you at least have a problem with the battery. 3 weeks, and now the car is sitting in cold weather, yes, it could just be a week battery. May or may not be damaged, but it is probably just not strong enough to start it.

I would just try to start the car with getting a jump start or battery jump box or something. You said it barely cranks, and if it is somewhat spinning, and just doesn't sound fast enough, that would mean that starter is probably fine, just not enough juice in the battery.

If the car is low on oil -add oil. No reason to start a car that you know is low on oil and you have time to add it. add the oil!