canI enable a disabled iphone 4 on itunes or do I have to go to the apple store

I apologise for being emberassingly non computer/electronically inclined so I'm not even sure how to figure out what operating system I have or any specs exce[t I believe I have an older iphone 4 and it is disabled due to being left in someones car that was towed.I finally got it back and was wondering if I can enable it from itunes or do I habe to go all the was to the apple store