Don't recall what specifically I was doing at the time but was maybe 7 or 8 years ago my computer got a virus and took me close to a week to fully gain control

Don't recall what specifically I was doing at the time but was maybe 7 or 8 years ago my computer got a virus and took me close to a week to fully gain control of my machine again. Only time I got actual warnings from Defender about something it couldn't erase.