I would personally recommend as a first step removing your web browser and reinstalling it.
If you use Chrome, Opera, Firefox, or any other web browser that does not come with your OS, then use Revo Uninstaller
to remove your browser and make sure there are no leftover files. After that, re-download your browser from Ninite, and then go to the botttom paragraph.
If you use Internet Explorer, open Programs and Features, hit
"Turn Windows Features On or Off", and uncheck Internet Explorer 11. Reboot and then do the steps again, but this time check the box instead of unchecking it. Go to the bottom paragraph.
If you use Microsoft Edge, just skip to the next paragraph.
Next, run an antivirus scan. Open the start menu, and search for "mrt". Hit Enter. Select "Full Scan", the click Next. It may take a loooong time to complete. Even if that comes up clean, try a scan with your favorite antivirus. If that comes up clean, then you probably have removed the virus.
Open your web browser and try a webpage. If that doesn't work, then you have a more complicated virus.