What do I do if my iPhone 5 or 5c gets stolen?

How can I retrieve a stolen iPhone 5/5c or 5S?
Is there anyway that I can find out who stole it or find the location of the phone or can I find the IP address?

It's far easier to preplan and buy an insurance policy that covers theft and loss.

In case of loss/stolen contact your service provider and police.

Hopefully you have find my iphone activated; if so go to apple.com/support and find out how to search for your miossing phone.
if not, then you need to report that phone as stolen & have it blocklisted, so that the other person won't be able to use the phone at all.

If it is hasn't happened yet you can download a program that will help you find your phone in that situation. If it has happened you are out of luck.

Have Find My iPhone installed to help with that. The IP address wouldn't do much, if anything.