git reset head

$ git reset --hard HEAD       (going back to HEAD)

$ git reset --hard HEAD^      (going back to the commit before HEAD)
$ git reset --hard HEAD~1     (equivalent to "^")

$ git reset --hard HEAD~2     (going back two commits before HEAD)

git reset --hard f414f31
git reset --soft HEAD@{1}
git commit -m "Reverting to the state of the project at f414f31"