I can't remember my passcode lock for iphone 5?

I already plugged it in to iTunes and tried rebooting it, but it said I need my PASSCODE to do that. So I don't know what to do. If I take it in to tmobile, and they re-start it, will All of my pictures and phone numbers be deleted? :/

I'm sorry but all of your photos will be wipes. This is a safety feature to make sure thief's don't gain access to personal files. If you back it up to a computer using a usb cable to itunes it will copy all personal files such as photos to your computer.
Hope this helps.