Forgot apple ID(email)

Hello.

I forgot my apple ID (email address), It's old e-mail address that i have never used. For this reason I can not turn on my ipad, When I turn on iPAD - activation lock on screen. .. in our country there is no official reseller/support apple. How can I bind my new e-mail (apple id) and my iPad? all the necessary documents after the purchase are preserved.

Im really sorry for any mistakes, i hope it's understandable.

Thanks.