Organization's Github account was deleted but there is backup of all the repos on hard disk. So will creating new repo of same names and then pushing the code restore the code base ?
(The account was deleted more than 2 months ago.)
That should work. If preserving the history is not important, collaborators can just re-clone the repo "fresh" from the new URL.
If you want to preserve the history you can use the
git remote set-url command from inside a current repository clone. That will switch the remote repository name from the old (deleted) account to the new one.