How can I find my iPhone if it is dead?

The phone must be turned on and connected to the internet in order to send a signal from its location. Check this link...

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

No matter how many times you post this question, the answer will not change!

If the battery is dead on your iPhone then it is not going to be able to connect to the internet to report its location. This calls for a search the old fashioned physical way.

Axel F.