Opera is an internet software suite that handles internet-based tasks, like sending and receiving e-mails, website display, chatting, downloading and reading web feeds, etc. After making any changes to the browser’s settings, you have the option to reset the browser to its default settings.
Restore Default Settings in Opera Browser
Before beginning, you need to display the hidden files on your PC. See this FAQ for more information on the subject.
Close the Opera browser, and go to C:\Users\user_name\AppData\Roaming\Opera\Opera\. Locate and delete the Operapref.ini file: