Q: lost iphone

You can't, other than by physically looking for it or by calling your number to see if someone answers.

You can place it in lost mode, which will be implemented if it ever goes back online.  If it does, you will be notified by email.  You might want to read this: http://support.apple.com/kb/HT5668.

What about if it doesn't go online isn't there another way??

I dropped my apple iPhone 4 in lake. It didn't have service but I had a lot of photos on it. Sometimes I connected to wifi to surf. But can I retrieve my photos ?