ONLY WORKS FOR GOOGLE PLAY STORE
Step 1) Buy the in-app purchase you want from the app itself.
Step 2) Go play.google.com and click the gear icon on the top right corner and select " My account"
Step 3) Find the purchase you made under the order history and click the 3 dots on the right and click report a problem
Step 4) Select this option " I purchased this but did not receive it"
And write this : When I tried to buy it, the app force closed and the stuff I want is not received "
Step 5 ) They will refund you immediately if the purchase is less than $10 and if it is more than $50, it will take a few days.