If you get a call from Microsoft or some other company saying there is a problem with your PC and they need to log in and fix it, hang up immediately
Legitimate organizations cannot see in your computer and call you to say they see a problem and need to fix. The IT department at your company may be able to get in and observe things in your work computer, but they have the administrator password and do not need to call and ask you to let them in.
These calls are phishing calls, they are trying to find people that will give them login information and let them in and then they will steal your personal information and also probably plant spyware and viruses on your machine if not doing worse. Do not give information to unsolicited calls.
If this article is too late for you and you already let someone in your machine from an unsolicited call, change all passwords on machine immediately. Immediately notify your bank and your credit card companies so they can either watch your account or freeze it or take other action such as changing password.
If you hire someone or have a friend to come work on your machine they will legitimately need the password to get in your machine. However you contacted them to work on the machine, this article is about unsolicited calls.
If you get an unsolicited call simply hang up on them immediately.