You can stash (save the changes in temporary box) then, back to master branch HEAD.
$ git add .
$ git stash
$ git checkout master
Jump Over Commits Back and Forth:
Go to a specific commit-sha.
$ git checkout <commit-sha>
If you have uncommitted changes here then, you can checkout to a new branch | Add | Commit | Push the current branch to the remote.
# checkout a new branch, add, commit, push
$ git checkout -b <branch-name>
$ git add .
$ git commit -m 'Commit message'
$ git push origin HEAD # push the current branch to remote
$ git checkout master # back to master branch now
If you have changes in the specific commit and don't want to keep the changes, you can do stash or reset then checkout to master (or, any other branch).
# stash
$ git add -A
$ git stash
$ git checkout master
# reset
$ git reset --hard HEAD
$ git checkout master
After checking out a specific commit if you have no uncommitted change(s) then, just back to master or other branch.
$ git status # see the changes
$ git checkout master
# or, shortcut
$ git checkout - # back to the previous state