If you had your remote’s password changed only, not the username, then try the following command to check remote’s info:-
git remote show origin
This will ask for your password for the given git user, fill that in correctly, and now try:-
git pull
or,
git push
It should work unless you have to change other things like username or remote URL, you can take a look at the following Git documentation:-
https://help.github.com/articles/setting-your-username-in-git/
https://help.github.com/articles/changing-a-remote-s-url/