Apple (and no one else) can not assist (with serial number or iCloud) in finding a lost or stolen iPad.
Report to police along with serial number. Change all your passwords.
These links may be helpful.
How to Track and Report Stolen iPad
http://www.ipadastic.com/tutorials/how-to-track-and-report-stolen-ipad
Reporting a lost or stolen Apple product
http://support.apple.com/kb/ht2526
What to do if your iOS device is lost or stolen
http://support.apple.com/kb/HT5668
iCloud: Locate your device on a map
http://support.apple.com/kb/PH2698
Report Stolen iPad Tips and iPad Theft Prevention
http://www.stolen-property.com/report-stolen-ipad.php
How to recover a lost or stolen iPad
http://ipadhelp.com/ipad-help/how-to-recover-a-lost-or-stolen-ipad/
How to Find a Stolen iPad
http://www.ehow.com/how_7586429_stolen-ipad.html
What NOT to do if your iPhone or iPad is lost or stolen
http://www.tomahaiku.com/what-not-to-do-if-your-iphone-or-ipad-lost-or-stolen/
Apple Product Lost or Stolen
http://sites.google.com/site/appleclubfhs/support/advice-and-articles/lost-or-st olen
Oops! iForgot My New iPad On the Plane; Now What?
http://online.wsj.com/article/SB10001424052702303459004577362194012634000.html
If you don't know your lost/stolen iPad's serial number, use the instructions below. The S/N is also on the iPad's box.
How to Find Your iPad Serial Number
http://www.ipadastic.com/tutorials/how-to-find-your-ipad-serial-number
iOS: How to find the serial number, IMEI, MEID, CDN, and ICCID number
http://support.apple.com/kb/HT4061
Cheers, Tom 😉
