How do I find a receipt purchase on ipad

You can use either method that I posted above, the emailed receipt, or if it was done within the last 90 days http://reportaproblem.apple.com (if longer ago than that you can view an account's full purchase history via a computer's iTunes : See your purchase history in the iTunes Store on a Mac or PC - Apple Support)

Receipt for what ? If you mean for an iTunes store purchase you should have (or get, if it's a recent purchase) an emailed receipt. Or you can view, and possibly get a duplicate receipt, via http://reportaproblem.apple.com

Sorry I still cant find it

Was the purchase within the last 90 days ? The 'report a problem' site only shows the last 90 days purchases.

There isn't a search facility on the purchase history on a computer's iTunes, you have to page through until you find what you are looking for.