Want to enable administrator account from standard user

Question

I had 1 account named "Tushar1" which was the part of admin group. It got corrupt suddenly, that's why I disabled it from users, and activated administrator account. Then I created new account named "Tushar" which became "standard user" by default which I didn't notice, and disabled administrator account. And as soon as logged into my newly created account, then I felt like I trapped my self. ;)) Please help me activating admin account.