A friend of mine's computer went out and she got a message saying call a certain phone number for help. She said they held her computer "hostage" and told her it would cost $300 to get rid of the virus blocking her use and could "find" and restore her information.
Apparently this is a common scam. If it should happen to you, unplug your computer and take it to a professional and let them debug it for you. It will cost you a lot less and they will be able to block the virus/hackers from entering your system again.
This is one of many computer scams. We need to remember that older adults don't have the years of experience that younger people have with computers, so they get taken in more readily! Never give up a dime until you check with a reliable professional about what you should do in these circumstances.