Got a 'your computer is locked' popup and called the number on it

Once the remote tool is removed, also look at Settings > Apps > Startup and your browser extensions for anything new, and check Settings > Accounts for a user you didn't create. If they had control of the screen, assume they could see anything that was open or saved on the desktop. Keep an eye on the bank account for a few weeks, small test charges often come before a big one.

That popup is a scam, the computer was never actually locked. What you need to do depends on how far the call went. If you only talked and didn't let them in: close the browser with Task Manager (Ctrl+Shift+Esc > end task on the browser), and when you reopen it don't restore the tabs. That's it. If they got you to install something (AnyDesk, TeamViewer, UltraViewer, anything 'support'): - unplug the internet straight away - uninstall that program from Apps in Settings - run a Windows Security full scan, plus the Microsoft Defender Offline scan - change your email and banking passwords from a different device, then turn on two-step verification If you paid them or gave card or bank details, ring your bank today and tell them it's fraud. And expect them to call back offering a 'refund', that's the second half of the same scam.