Are you using the Opera web browser, but you somehow manage to install a version in another language than you preferred? Or maybe you simply want to change the language for some other reason?
I recently wrote an article on how to setup a proxy in Opera and for that article I needed a screenshot. However, since my Opera installation was in another language it would create a poor and hard to understand screenshot for my article which was to be written in English. So, I looked for a solution on how to change the language of Opera without installing the entire browser over again, and luckily I found the answer. So, if you want to change the language as well, follow these instructions.
I was using Opera 16 as I did this, and later upgraded to Opera 17 afterwards, and it have worked on both versions, so hopefully it will work on your Opera version as well.
Change the language of Opera
First step is to close your Opera browser and find the folder containing the Opera files. This could be something like: C – Program Files – Opera
Open the file installer_prefs.json in a text editor and change the language (all available language codes can be found in the localization folder)
Save the file (make sure to save it with the same name, and do not let your text editor add a .txt extension to the file name)
Open Opera again and you should now be able to use it in your selected language.
A common mistake when changing language
Make sure to use language codes that exist in the localization folder.
If you are not allowed to save the installer_prefs.json file because the directory is secured, then copy the file to another location, edit it, and then copy it back to the original destination using Windows Explorer. Give the needed permission when copying to overwrite the original file.