Error with Apple ID after upgrade i0S 9

Hi.

After my Ipad 2 was upgraded to iOS 9.1. It´s asking me to log in with my Apple ID account. I write username and correct password but error Message appears: Imposible to log in. I check outside account and password in my pc and they are working well. Change password as well but it´s not working only in Ipad after upgrade. How to solve this problem ??

Please your help.