git reflog //You can use git reflog to find the SHA1 of the last commit of the branch.
From that point, you can recreate a branch using
git branch branchName <sha1>
user@MY-PC /C/MyRepo (master)
$ git branch -D master2
Deleted branch master2 (was 130d7ba). <-- This is the SHA1 we need to restore it!
user@MY-PC /C/MyRepo (master)
$ git branch master2 130d7ba