Infection with virus « Gendarmerie nationale ».

Hello,
I recently bought a second hand computer with no antivirus installed. I was browsing on the Internet when a add popup infested my computer with a virus called « Gendarmerie nationale ». This virus blocked my computer and I succeeded in unlocking it looking at an Internet procedure. After that, I installed the Avast antivirus and I made a scan of my computer. There were viruses detected and some of which couldn’t be removed. I tried to come back to a previous System Restore Point and made another virus scan but viruses were still present. I made several scans and I tried to remove the infected files but the viruses at still present. Is there anyone to help me please?
Best regards.

You need to start a topic in the Malware Removal forum ....

May I bring your attention to THIS topic which you should read before posting for help. Specifically THIS section, which tells you what information we require before we can help you and why we need it.

Hello jujucds ,

You have created the new topic for your malware problem in this same forum, which is not the correct one.

I have moved it to the malware removal forum:
viewforum.php?f=11

This is your topic:
viewtopic.php?f=11&t=59257