Well just before closing I had downloaded some antivirus applications and some pdfs.

@naheed Well I downloaded Opera browser 4 months back. This error has occured only on 11th Nov 2020 morning. Then I checked for the solution on Opera forums. I had noticed one of them was 2018 solution. First, I tried installing opera even if the opera existed, cause they said that it might help repairing some of the files. It did'nt work. Then I uninstalled Opera from my pc excluding the personal data and reinstalled Opera afresh, but the problem still persists.
It doesnt open up, so I couldn't disable any extensions as such. I guess the last time I updated Opera was like a week ago.
It happened suddenly, the previous night too it was working fine. Morning too, after sometime I closed. Since then it was'nt opening

I tried the previous 2018 thread but it doesn't work. I am using Windows 10. It had started since the morning of 11th Nov,2020. I am using Windows 10. Also, my Opera GX works but not Opera browser.