Mac is locked up. hjow do I unlock?

See if you can force quit out of Safari. If you can the relaunch Safari with the Shift key held down to reset it's caches.

If you can't force quit Safari shut down the Mac by holding the power button down till it shuts down. Then reboot and restart Safari as above.

If you still have problems download and run the free version of Malwarebytes. Did it find anything?

Lastly if you're still having problems download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

Before running Etrecheck assign Full Disk Access to Etrecheck so that it can get additional information from the Console and log files for the report:

Then we can examine the report and see if we can determine what's causing the problem..

Hello,

That is defiantly not Apple’s doing. These are ransom websites designed to make users think they are something they are not. In Safari pull down the Safari menu -> Preferences. From here verify that your homepage is correct. Under extensions remove anything untrusted listed. It is also good to keep the pop up blocker enabled.

Hello,

Can you please elaborate more on your problem?

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