Bugged out computer [Closed]

Hi! I tried to downlad something on my computer and I'm afraid it contained a virus for all I see now are random popups and downloads I didn't get. I also can't open my windows start button to factory reset the computer, as I've done in the past due to the same problem. Any tips on how to get it working or how to get to my settings? It won't go out of desktop mode ever since I downloaded windows 10 and I really need to use my computer soon. Thank you!