How to do Undo things done mistakenly in GIT

Undo git add command

git checkout -- <filename>

git checkout <filename>; i.e. checkout repository's version

git reset --soft HEAD^

*This command would undo commit, but would keep changes so that we can re-modify and re-commit

With git log check which commit is one prior the merge. Then you can reset it using:

1. git log --oneline -n 2

2. git reset --hard <commit_sha_previous_to_merged_one>

OR

git reset --hard HEAD~1