Help!

I searched the answer for you, but it seems pretty complicated. I'd go to a professional at Best Buy (or the Future Store if bạn live way up north) hoặc some electronics store and ask them for help. Geek Squad is a great place if you're going to get help. Their located in Best Buy. Good luck! :3
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Sorry, I don't have Nokia C2-O2

I think I have about the same cellphone as you. It's simple. Just go to the Menu, and it should be right there in that list. At least, that's how it is on my cell.