How to restore a disabled iphone without service?

I bought an iphone and it is disabled, it doesn't have service, and it won't let me restore it on itunes?
Any ideas on how to restore it? Thank you!

Added (1). I tried to restore it on itunes, it says i need to enter the password, which I don't have.

Download iTunes, plug it into your computer it'll pop up. Doesn't matter if its locked. There's a big button that says restore.

Connect to computer. Hit restore. Wasn't that easy?

You have to put it into dfu mode then restore it
it has worked for me