Do I need a new battery?

If this is the first time it has been jumped - you will be fine.
Was it just DEAD or did u leave an accessory on for it to drain?
If you couldnt find evidence of a light on, or some other drain - there is a different problem you need to address.

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When you cut the car off, if you can't start it back up, then yes, it needs a new battery. If the battery light is on while driving, then you may need a new alternator.

Well, as long as there are no lights on the dash lit up, I would suggest changing the battery.....

Most shops can test your battery too before you go and buy a new one. Have them test it first.