I put in a new HD ... no os. Put in a bookable usb with Linux desktop 20.04 and did nothing.... froze on the F2 Setup - F12 Boot menu screen. Do not have a CD Rom with Linux, only a USB. PLEASE HELP....

Not enough infomation to give any advice.
What did you use to create the bootable usb? Full name of the iso that you used?
System specs(processor video adaptor ram drives), how old is the system what windows came on it originally?

That's expected. Hard disks are normally not sold with an OS on them.

By freezing, do you mean that hitting F2 or F12 has no effect?

My guess is that you have to set up your computer before inserting the USB drive. Go into the F2 setup screen and ensure that the computer can boot from USB.

Another possibility: Your computer is simply broken and will freeze at that screen, no matter what you insert or don't insert.

Another possibility: A bad hard disk contact confuses the computer. Also try booting from the USB driver without the HD inside.

Or perhaps the USB connection is bad. If you have several, try another one.

Or the USB drive has issues. Try another drive.

Unfortunately, there are many possible reasons for freezing your computer. The above list is definitely incomplete.

What kind of computer is this?

It's a shot in the dark, but you may have to enter the BIOS/EFI and enable/select booting from USB.

As above, you need to set up your computer to boot from USB before internal hard drive.