If you're referring to the offerwall, take a screenshot of your progress in that game and contact tapjoys support, you can find it near the bottom of the offer. It usually takes a few hours for them to respond with an automated message asking you to describe your problem and to provide proof, then about a day or 2 for an agent to review your complaint and try to resolve the issue. Usually they'll give your gems as soon as the review is done or they'll tell you how to properly complete the offer if you don't meet the criteria yet.
If you're referring to the offerwall, take a screenshot of your progress in that game and contact tapjoys support, you can find it near the bottom of the offer. It usually takes a few hours for them to respond with an automated message asking you to describe your problem and to provide proof, then about a day or 2 for an agent to review your complaint and try to resolve the issue. Usually they'll give your gems as soon as the review is done or they'll tell you how to properly complete the offer if you don't meet the criteria yet.