How to quickly undo staged and unstaged changes in git?

git reset HEAD
git checkout .

git reset HEAD will unstage all changes and git checkout . discards all the changes.

You need to use two commands: git reset --hard and git clean -fd.git reset --hard will undo all staged changes and git clean -fd, unstaged changes (files and directories). You can create a alias that will do the two commands. For that, just add the following lines in your .gitconfig:

[alias]
  undo = '!git reset --hard && git clean -fd'

You can use git clean

$ git status -s
?? oops.txt

$ git clean -f
Removing oops.txt

$ git status -s

More info:

Cleans the working tree by recursively removing files that are not under version control, starting from the current directory.