Found this answer on Stack Overflow very useful, so thought I’d share it here:

If you want to revert changes made to your working copy, do this:

git checkout .

If you want to revert changes made to the index (i.e., that you have added), do this:

git reset

If you want to revert a change that you have committed, do this:

git revert ...

Source: How to revert all local changes in a GIT managed project to previous state ?