First, make sure that you are logged in to the app. Please follow this link to learn how to check if you are logged in: https://androidpuzzlessupport.zendesk.com/hc/en-us/articles/6418593069329-How-to-check-if-I-am-logged-in-to-the-app-
Please, note, that you should be logged in with the same details that you used for the original registration in the app. If you enter new details, it will create a new Magic Puzzles account.
If you are logged in to the app correctly but your coins are still missing, please contact us so that we could check your account. Don't forget to give us your game ID.