Thanks for your reply to @mehrfatima2530 and just to add:
Fiverr is slowly leaving aside the automatic 3-day marking system, so some sellers now have to mark the orders as complete by themselves.
This new way of marking orders is not yet available to me, and according to your question, neither for you, but eventually it will, so keep it in mind for when you get it.
Regarding not hearing from your buyer, some of them will disappear after receiving their order never hearing again from them until they place a new one. It can also be possible you’ll hear from your buyer asking for revision during the marking period or once the order is completed.