If you delete too quick your branch before merge some change, and delete it from your local and remote repository, don't panic.
First, find the commit SHA1 with this command :
git fsck --full --no-reflog | grep commit
Now you got your SHA1, feel free to
git checkout [SHA1] to test if you got all you want and merge this commit ID on your dev branch, or restaure the previously deleted branch by using :
git branch [branchName] [SHA1]