So I tried upgrading my prestashop version from 1.7.1 to the stable 1.7.2. (something) but after the upgrade it didnt look very good so i tried rolling back but my website crashed, then i mistakenly deleted my database with the help of my provider 1&1, then I hired a person to bring it back. the front office is back but when i try logging into my back office it says user doesnt exist. how do i gain access to my back office??