Scam Library
Someone remotely accessed my computer
What to do in the next few minutes if a stranger had control of a Windows PC.
If someone you did not invite is connected, or a caller is telling you to leave a remote session open, disconnect that PC from the network. End the remote-support program if you can, or shut the computer down. Do not read them codes, and do not stay on the phone while you do it.
Write down the name of any program they asked you to install. If money, a bank, or email was involved, call that company using a number you look up yourself, not a number they gave you.
Then check whether remote-access software is still installed or set to start again. A free Remote Access Check looks for an active session, a recently installed remote tool, and suspicious persistence. Guardian is what stops the next one: it refuses any new remote connection until you, or a person you trust, actually approve it.