If you tried the on and off button LOL and that didn't sort it then try re-setting the device. This however you may need to contact Apple to help you reset, however make sure all your data is backed up on iCloud or what other software you use. Re-setting will delete all your installed apps anyway and bring your phone back into the condition it was when you bought it. So that means that numbers may go too!
However if you call Apple up they may have other alternatives that may work better, though that's the advice they usually give, and it takes a LOONG time because those Apple call centre people do not stop talking...and I mean about their life not the phone! LOL Good Luck!