SHELL

git checkout to previous commit

# git: checkout to previous commit

git checkout HEAD~X # x number of commits to go back

# Go back one commit:
git checkout HEAD~1

git checkout previous commit HEAD

git checkout <commit_id>
git checkout -b <new branch> <commit_id>
git checkout HEAD~X // x is the number of commits to go back

git checkout previous commit

git reset --hard HEAD~10
To rollback 10 commits back:

git checkout previous commit

$ git reset --hard <commit_id>

checkout master with previous commit

git checkout 307a5cd        # check out the commit that you want to reset to 
git checkout -b fixy        # create a branch named fixy to do the work
git merge -s ours master    # merge master's history without changing any files
git checkout master         # switch back to master
git merge fixy              # and merge in the fixed branch
git push                    # done, no need to force push!