i lost my ipad and i need the serial number and IMEI , please help me how?

If you have registered your device, you can go to https://supportprofile.apple.com/ and log into your apple id. Your devices appear there with serial numbers.

Additionally, your serial number is included on the original receipt when purchased at any Apple Online or Apple Retail store, or any Authorized Apple Reseller.

In addition to what jaredfs provided, you may find the following of interest:

Find the serial number and other information for your iPhone, iPad, and iPod touch - Apple Support