I can’t reinstall the macOS that I accidentally erased

Hi Kathyb1022,

First:

If you don't know whether your particular Mac does, or does not, have the T@ security chip

See this article:

Mac models with the Apple T2 Security Chip

https://support.apple.com/en-us/HT208862

Then:

You might want to follow the reinstall steps in this online Apple Support article:

Erase and reinstall macOS

https://support.apple.com/en-au/guide/mac-help/mh27903/mac

Hope this works for you :-)