You should try two things less drastic than a Windows install.
Maybe that should be three things.
1.)
Create a new user account with Administrator level, log in to that new user and install Opera again. It just might work.
2. )
Download an older version of Opera. Try again.
3. )
Turn off you Anti-Virus and first test the Opera installer for compatibility issues.
Make older programs compatible with this version of Windows.
Then there is the question of hardware issues.
Thank you for your suggestions.
I'm currently using Opera 49, I also have versions 20 and 37 and I'm reluctant to downgrade to an earlier version. The reason being to do with the two Opera Software folders which are to be found in the Application Data Folder on the C: drive, one in the Local folder, the other in Roaming.
Just in case I have to do a re-installation of the Windows OS I keep all my data files on a portable disc drive, which has several partitions one of which holds all my software installation programs. These can be found in sub folders for audio, browsers and graphics for example. In the browsers folder I have a folder named Application Data. this has two sub folders named local and roaming. Each of those sub folders have two sub folders one for Opera, the other Firefox.
Whenever I'm about to a re-installation of Widows, I'll go into the application folder on the C: drive and copy the Opera and Firefox folders and paste them to their respective folders on the portable disc drive. After completion of the Windows re-installation, I'll begin re-installing my programs. Once the browsers are installed, I'll do the reverse by copying the aforementioned folders from the portable to the C: drive. So that when I open Opera or Firefox for the first time, they are exactly how they were before I did the re-installation of Windows.
The thing I've found is, if I save the data from say Opera 49 it is incompatible with Opera 37 for some reason.