Is there anyway to fix this?
For your keys and customizations (shift redeemed customizations), send in a support ticket with Gearbox here
https://gearboxsoftware.zendesk.com/hc/en-us/requests/new
As for your badass rank, make sure you are connected to the internet. Then load up each one of your characters one after the other.
That should restore most of your lost rank.