I believe I got a virus from a download a few days ago, however I don't know exactly what it came from. Windows Defender was working for the first 2 or 3 days, removing some files. Then, files with random names would appear the next day. These include applications that create chrome popups that I can't do anything about. I also see a large Yahoo icon on some websites. I appear to have gotten rid of some files however the virus is definitely still here. Today, Windows Defender was turned off. It reads: Threat service has stopped. Restart it now." with a large Restart button. However nothing happens when I click this button. Also, if I open Window Defender Antivirus and try to click Start Now, I get an error message that says "This service couldn't be started." If i try to download Malwarebytes, my pc instantly blocks and removes it, which i have found no way to get around. I need help finding the source of the virus and getting rid of it, because there are still some popups and random command prompts that open and close before I can read anything. If you need more details please ask, thanks.