Sorry to hear that!
If your request expired, you can always send a new one over to the celeb or send one to a different celeb altogether.
If you sent your request through the website, the hold on your card should fall off in a few days depending on your bank.
If you sent your request through the app, you should see a new Cameo credit balance in your account that you can use on a new request, Cameo Direct Message, or Cameo Call!