When we do human things to dogs like petting them, we have to make it worth their while. Dogs aren't born liking being touched and might not want to be pet by us.
If your dog used to like being petted and now doesn't, she might be sore or have a medical problem. Check with your vet.
Learn more about how to approach a dog for petting so they learn to enjoy it, watch our video:
https://youtu.be/8AHo8MMe-dk