Found an iphone 5, want to unlock it?

I was in the jungle gym at a park and i found an iphone 5.It said there was no sim card, so i popped the slot out, and yes it had no sim card inside of it. The past owner had a lock on the phone, not numbers but the keyboard lock. I was going to put my sim card inside it from my 4s, but i found they are different sizes. I don't think they can track a phone without a sim card inside of it. I basically just want to unlock it, reset all the settings, and make myself a new phone. What do i tell the store, and what should i do, to accomplish my dream of having a working phone? My 4s literally broke the day before, and i need all my information for work.

I want my phone back please.

What you can do is reset the entire phone and then go to a store or call your phone service to have the phone operated.

Plug it into your computer and you can restore the whole phone in iTunes.

If it has iOS 7 then you have no way to turn off find my iphone and have no way to wipe it as both are security features the require the apple ID and password. Any attempt to connect it to the internet will notify them where the phone is located.

Return the phone you stole to the police. Stolen phones can be tracked, so beware. If you want a phone of your own, buy one, like everyone else.