Any user always wants to have option to reset a browser settings to its default after making some changes to browser settings, if you are a Opera user, you can’t find any option provided in its browser settings to restore default settings, let ‘s take a look how we can reset Opera to its default settings.
UPDATE: If using Chromium based Opera, check this: Opera 50 : How to Restore Opera Factory Settings
Though you can uninstall Opera, your Opera profile will not be removed. When you install newer version of Opera, preferences saved in the older profile will be retained for newer version as well. Then you may not able to spot or identify new features or changes in the latest version.
Resetting Opera settings to default
All you need to do is remove configuration settings file “operapref.ini” located in Opera profile folder.
1. Close the Opera browser.
2. Go to “C:\documents&settings>username>application data>opera>opera>profile” and remove Operapref.ini file [Windows XP]
“C:\Users\<username>\AppData\Roaming\Opera\Opera\ “ and remove Operapref.ini file [Windows Vista and 7 ]
Make sure Explorer to show hidden files and folders by selecting Tools menu and folder options.
3. Now open Opera browser, Opera will automatically rebuild its default configuration settings.
Update: The above said instructions applies to Opera 12.x and earlier versions only.
Uinstall opera. Erase registers via REGEDIT > registry editor. Delete operaprefs.ini and other files and empty the “trash”. Sorry for some verbal expression (I am from Czech republic).