I (stupidly) accepted a free download of attractive backgrouds.
When I next started up, the first thing that came up was a supposed antivirus programme seemingly scanning my Computer for problems.
When finished it gave the option "Fix".
This took me to a site which asked me to buy the product.
I turned it down and attempted to delete it.
After much time, I eventually deleted off screen using task manager.
The screen then froze, and windows would not load, so I could not do anything about it.
I have tried in safe mode, to no avail.
It is obviously some kind of blackmail.
Is there any way of doing a system restore through the F buttons ??
Please help. I am using a borrowed Computer at the moment.