The discard (that you can see in "Undo Button in GitHub for Windows") is available to
reset files added to the index.
That means you added files, and reset them before any
The GitHub for Windows/Mac won't help you there.
You need to recover those files from the git repo (
--unreachable --no-reflogs --no-cache HEAD).
See "Recovering added
file after doing
git reset --hard HEAD^" for more.
Benz_java mentions "restoring lost commits", for looking in the reflog for