Though you might need to contact Google Play if you are experiencing problems with the Store itself, there are a few things you can try first, to see if they get you back on track
The first thing to try, is to restart your device. This usually reconnects and refreshes your links to the Store.
Also, make sure you have the latest update of the Google Play Store app installed.
Finally, clear the Google Play Store cache by using these steps:
Additional support for purchase problems when using the Google Play Store can be found here: https://support.google.com/googleplay/answer/1050566
If you have any further issues which are not resolved by checking the above links, please get in touch.
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