How can I undo every change made to my directory after the last commit, including deleting added files, resetting modified files, and adding back deleted files?
First, reset any changes
This will undo any changes you've made to tracked files and restore deleted files:
git reset HEAD --hard
Second, remove new files
This will delete any new files that were added since the last commit:
git clean -fd
Files that are not tracked due to .gitignore are preserved; they will not be removed
Warning: using -x instead of -fd would delete ignored files. You probably don't want to do this.