Hi. I'm Brian and I'll try to help.
Explain, please, what you mean by "Microsoft isn't working." Microsoft is a company. It doesn't run on your computer. What program are you trying to use? Do you mean one of the Microsoft 365 apps like Word, Excel or Outlook? If not those, which one? What happens when you try? Do you receive an error message? If so, please include it here exactly as it appears on your screen. Also, please explain what "yahoomalware" is.