ABC and keyboard symbol at top right of screen

That will occur if you have more than one keyboard selected in Keyboard Preferences.

ABC is a type of keyboard. The letter arrangement is the same as US "qwerty" (for example) but special (non-alphanumeric) characters will be mapped to different keys.

If your password contains those non-alpha characters click that icon in the menu bar and select the keyboard you would normally use from the dropdown menu.

infradog wrote:

My system is classic English qwerty.

As mentioned earlier, click on the ABC up on the corner and go down the list and select US as your login keyboard and see if that helps.

Could you post a photo of your keyboard?

infradog wrote:

A long alphabetical list of what appears to be keyboard options.

If your hardware keyboard is US English, then try selecting US instead of ABC in the login screen list.

if your hardware keyboard is some other language, tell us which one.

Also answer the earlier question about your system preferences/ keyboard/input sources list

The ABC at top right just says that you have a qwerty keyboard active. I don't think it is playing any role here. Are you just saying that your keyboard does not work at all when you try to log in? If so, can you try another one?

Thanks!

Does your password contain any characters that are not printed on the keys?

Can you verify that this keyboard is producing the characters you expect by using it with some other machine?

Can you borrow another keyboard to try with your mini?

infradog wrote:

My keyboard works fine. I type in my password as usual and it is rejected. ABC was never there before so suspect it may have something to do with this

ABC is exactly the same as US and is a standard English keyboard layout. Is that what you normally use? If you click on it you will probably see other choices.

One possibility is that a key like shift or option has for some reason gone bad, so that the wrong characters are being produced. It would be nice to be able to check that.

Otherwise you might try

https://support.apple.com/en-us/HT202860

My login is in middle of screen. Not understanding your issue? Can you use your phone to show photo of screen? Be sure and edit any names or personal info that might be in photo before posting.

You may be able to just start typing, since the cursor will default to the login dialog upon restarting your Mac and selecting the user.

What do you see when you click on the ABC?

To have the Input Menu appear on the login screen like that is expected with some system settings.

Is your hardware keyboard US English?

What is on your list in system prefs / keyboard / input sources?

John Galt wrote: ABC is a type of keyboard. The letter arrangement is the same as US "qwerty" (for example) but special (non-alphanumeric) characters will be mapped to different keys.

That's not correct. ABC and US are identical for all characters. The only purpose of having a different name is to accomodate users who don't want to use a layout named for a particular country.

(Perhaps you were thinking of the layout called "ABC Extended", which is in fact different from US)

infradog wrote:

I keep entering passwords and I never get a message saying I have tried too many times

That sounds like perhaps the OS is frozen. You may need to try the things mentioned at

https://support.apple.com/en-us/HT212190