I asked for a refund and the game stopped working

That is intended. A game is locked the moment a refund request is submitted, not when the refund is paid — so it cannot be installed or played while the request is open, and the store shows it as Refunded rather than owned.

If the request is turned down, the purchase goes back to normal and the game is playable again. If you changed your mind before anyone has looked at it, say so through the contact form.