Here is the solution for above issue, if you had deleted the stash by mistake:
Open a terminal window and cd into a folder under the repository. Then:
git fsck | awk '{print $3}' > fileOne.txt
cat tmp.txt | xargs git show > fileTwo.txt
Now open fileTwo.txt in editor, locate your lost code, and find the commit-id on top of it. Then apply the code:
git stash apply <commit id>
rm tmp.txt fileTwo.txt
This saved my life! I thank to the git creator Linus Torvalds for keeping deleted stuff in the git database.