How to access a stolen iphone 5?

I was clubbing the other night and found an iphone 5 in the bathroom stall.
I obviously took it with me seeing as though there was nobody around when I found it.
There's a passcode on it and there location is on.
How am i able to get into the phone when there's a password? And am I able to restore the stuff on my phone into theirs? And if i do that and they try and track it, could they even see where it is? The phone is currently turned off, does that mean they have no way of tracking this device?

You need to try to find the person who lost it. It is still stealing. Besides that the person will call their carrier (or Apple) and tell them there phone is lost, then the carrier will flag the phone as stolen/lost. The ESN will be unusable and you will basically have an iPod touch.

IPhone can be found anywhere.off.dead. Even broken I'd find the owner As soon as possible so you don't get in fraudulent trouble for not reporting that you found it.

Hold down the home button to access Siri, then tell it to call home, or some other person that might know them, such as brother or girlfriend/boyfriend. Then you can ask who's iPhone You are calling from and if you're lucky then someone will tell you.

It can be tracked.
email me i can help

Yep the can track it. And since most iPhones have Find Mu iPhone turned on, all the owner has to do is log in onto their pc into their account and they'll see the address its located at.

I'm afraid you'd better go to the clubbing and return it to the loser because it's really easy for him to track it.
If he has set up Find My iPhone/iPad on your device prior to it getting lost or stolen, then gose to https://www.icloud.com/...cloud.com/ in your web browser. When he logs in, Find My iPhone/iPad will immediately begin trying to locate your device.
If he has not done that, applying some anti-thief app like ilostfinder is a wise choice.

It will take pictures of the thief when she/he tries to open his device and then send those pictures to his email.

Hope it helps.

You'd better try to return it to the owner first. For there are many users who may put some anti-theft or monitoring software on their phones to protect them. You may get into trouble if there's such app applied on the phone. I'm using ikeymonitor on my phone and I can remotely monitor phone even when it is away.