Undoing accidental git stash pop

Solution 1:

Try using How to recover a dropped stash in Git? to find the stash you popped. I think there are always two commits for a stash, since it preserves the index and the working copy (so often the index commit will be empty). Then git show them to see the diff and use patch -R to unapply them.

Solution 2:

From git stash --help

Recovering stashes that were cleared/dropped erroneously
   If you mistakenly drop or clear stashes, they cannot be recovered through the normal safety mechanisms. However, you can try the
   following incantation to get a list of stashes that are still in your repository, but not reachable any more:

       git fsck --unreachable |
       grep commit | cut -d\  -f3 |
       xargs git log --merges --no-walk --grep=WIP

This helped me better than the accepted answer with the same scenario.