Note: These commands will stash all the files after add, so if you need some files just do git add to keep or else all will be gone.
git stash --keep-index
Since git 2.13, there is a command to save a specific path to the stash:
git stash push <path>
As this command will push all staged and unstaged files in the path but if you use the above command --keep-index it just leaves the index alone after the stash is done.
For more information about installation of git and common git commands please go through the following link: