Possible scam

Caller: They said it was Windows Defender

I clicked on the messenger symbol on my FB page as it said there was a new message for me although it was in a greyed out box at the top right hand side of my FB page, which now that I think about it, did look a bit suspicious. As soon as I clicked on this the page froze and an audio message came through my headphones saying I had clicked on a possible virus in FB and that Windows Defender had blocked something suspicious, that I was not to turn my computer off but to call this number. I called the number, he said he was from Windows Defender but when I queried it and asked if it was a scam he said no but then when I said I would just quickly Google the number, he hung up and the call was disconnected.

Facebook's Messenger app had a message saying someone was trying to reach me. Looked like a Messenger alert, not a scam. I stupidly clicked, and got what looks like the Micrsoft security window pop up and a recorded message saying to call the above number, whcih was displayed at the top of the screen. it also said my FB account would be permeneantly deleted if i didn't call, and to not shut my PC. I was immediately suspicious. It had locked me onto the warning screen and i couldn't toggle to Edge, Chrome, etc. So i shut down manually, re-booted, did a scan with MS Defender (just in case), and no viruses detected. DO NOT click on such a link, and DO NOT call the number. I don't know how FB lets these 'messages' appear in the first place.

Caller: screen warning must call number

"Windows Defender has temporarily disabled your computer..."