git issue, fatal error: your current branch appears to be broken

Something went wrong while I was doing some action with git as given below,

• I was working with sub-branch
• Pushed new commits to the remote branch using git command
• Changed branch to the main - master branch

When I hit command “git checkout master”, my computer gets an unexpected force shut down twice. (I never tried the same more than that). After that, I turned on PC (Running with Windows 7 since last 5+ years) and was observing files under my master branch, it shows all files marked as new files.

If I hit git log command, it shows below error:

> git log
fatal: your current branch appears to be broken

Is there any way to restore my branch without deleting it?

Ref: Git