I forget my apple id and password and cant activate my ipad

Have you used the same account on your computer's iTunes and have any of the account's downloads in its library : Recovering a forgotten iTunes Store account name - Apple Support

Or you could try finding it via http://appleid.apple.com : How to find your Apple ID - Apple Support

If you still can't find it, and if you were the original purchaser of the iPad (i.e. wasn't bought used) then you could try going to an Apple Store (make a Genius Bar appointment if you do) or try contacting iTunes Support online (http://www.apple.com/support/itunes/contact/) and see if they can/will remove the iPad from the account - they are likely to want to see proof of ownership before they might help e.g. original receipt with the serial number on it