SHELL

fatal: Authentication failed for Git

git remote -v
git remote remove origin
git remote add origin https://<your-username>:<token>@github.com/<username>/<repo-name>.git

authentication failed for git

WIN+S (windows search) > Credential Manager > Credential Manager > Edit
   --OR--
WIN+R (windows run) > rundll32.exe keymgr.dll, KRShowKeyMgr > Edit

authentication failed github

Authentication failed.
You may not have permission to access the repository

Stepa to fix issue:

1.Remove repo from GitHub Desktop
2.Logout from your github account [File > Options]
3.File > Add Local Repository
4.Repository > Repository Settings and change to https URL [Important tweek]
5.It started working back for me.