My car won't start -_-

It worked fine until a few days ago, I was taking out all the seats and upholstery to clean...and I was listening to the car radio while I was doing all this (not smart). And now it doesn't start...I thought I killed the battery but a friend said that wasn't it...I also took the alternator to a store to get tested and it was fine. What could it be if its not the battery or alternator...I also don't think my friend knew what he was talking about so is there a way to test the battery

You try jumping it off?

Sounds like a dead battery to me. I wouldn't take somebody elses word on it that it's not the battery until I test it myself. Hook a battery charger to it and test it. No battery charger? Try jumping it. All else fails, take it to Autozone or someplace and they can test the battery right there for free.

Does the motor turn over. If it does then its not the battery. If it doesn't then the battery is dead.