Fixing Typo3 error after an extension/plugin upload

PROBLEM SOLVED, I WILL CLOSE THIS PROPOSAL. THANK YOU ALL ! ***************************************************************************************** --------------------------------------- Hi, in my typo3 backend I have tried to install a plugin/extension, the "powermail" from the link here ([login to view URL]) . It was stated it is compatible with my Typo3 ver. 7.6 I tried to upload it in the backend (extensions, upload) and it gave 2 warnings: 1) The PHP version is too low (5.6) and it needed to be at least 7 2) This extension was created for Typo3 ver.10 and above; I have easily changed the PHP version to 7 (via CPANEL, see picture) , with no problems and logged in to my Typo3 backend. After that I have tried to push the instal of "powermail", even if the system gave a warning it's not made for my version of typo3. 10 seconds later the typo3 crashed and gave the warning from the picture attached (Class 'In2code\Powermail\Utility\ConfigurationUtility' not found) After that I could not login to the backend and the WEB page itself is not to working. I found this on Google as a possible solution but I'm not willing to risk on my own ([login to view URL]) Anyone who will work on this should not delete anything, the site should be brought back to normal functions and the backend login also. You can access the site by FTP or CPANEL (from picture). ***************************************************************** PROBLEM SOLVED, I WILL CLOSE THIS PROPOSAL. THANK YOU ALL ! *****************************************************************************************