I said I told my girlfriend a joke and she overthought it and kept ignoring me. What should I do?

Coax! You must explain and explain again, and explain clearly. The girl says she doesn’t want to hear it, but actually she still wants to know. The best thing to do is to find some evidence or do something to make the other party believe that you love her! If your mouth is sweet enough, then say thank you with sweet words. It’s so sweet that I don’t need you to apologize! (*^__^*)

Hehe... I hope you are satisfied with my answer! I hope your misunderstanding will be resolved soon!