Error profile login

Did you create a Time Machine backup prior to doing that? If so now is the time to use it: Restore your Mac from a backup - Apple Support

Changing a Mac's user name requires this specific procedure: Change the name of your macOS user account and home folder - Apple Support. Please describe what you did in lieu of that procedure. It may not be possible to correct it without erasing the Mac.

jafferuddin Said:

"Error profile login: I recently tried to change my username Now I can't get into the profile in system preferences and also the username is not changed and it still shows 'macbook' but the password isn't working for anything"

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Troubleshooting Password Issues After Password Change:

A. Restart your Mac:

Having just made this change, restart the Mac.

B. Boot into Safe Mode:

Try logging in using Safe Mode (Hold down shift key upon boot). See if you can log in. Items only load as they do by default, while you are booted into Safe Mode. All caches are set aside.  Go Here: Use safe mode to isolate issues with your Mac - Apple Support

C. Reset the SMC and your NVRAM:

(applies to Intel-Based Macs Only). Sometimes when changes are made to the system(i.e. updates), system configurations (i.e. for sound) become manipulated, technically. So, reset the SMCand NVRAM.