i want a serial number of my phone because my phone has stolen

As a starting place, here's what to do if your iPhone was stolen. As noted in the linked-to article, here's what to do to to find the serial number. Specifically, If you don't have your iPhone you can locate the serial number:

• If you have your product's original packaging, you can check the barcode to find the serial number.\ and
• You can also find your product's serial number on the original product receipt or invoice.

Good luck!

JDee