Now git doesn't work."
This was the least obvious one to fix when I had to rescue my keychain last week after messing up a password reset (protip: don't immediately forget what you changed your password to).
I also had to run
git config --global credential.helper osxkeychain and then enter my username/password on the cli for the first commit. After that, all seems well.
Also, changing your password over wifi is a risky venture. You might end up blocked out of the network. I'm not sure if there is a best practice for doing the swap over - but I found having access to a Windows PC useful. And setting up fastpass (which I only did after having to validate my ID manually. That's taking a photo of your BBC ID and sending it to the IT service desk email).