In order to locate your ipad it will need to be turned on and connected to wifi.
You can also lock or wipe the device via icloud.
was it lost somwhere at home or work or stolen?
Reporting a lost or stolen product
http://support.apple.com/kb/HT2526
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
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
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