Check your “order status”.
If it’s “Late”:
When an order is marked as Late, the seller missed the expected duration time to deliver. Buyers are entitled to cancel their order if there’s no further response from the seller. If a seller does deliver soon after the order is marked as late, the buyer will be given the chance to request revisions or complete the order and rate their experience accordingly.
If it’s “Very Late”:
This means 24 hours have passed since the order is marked as Late. Similar to what’s mentioned above, the buyer is now able to cancel the order within the order page (also using the Resolution Center). When an order is canceled from this status by the buyer, a seller is given a negative rating.
I once had a seller not deliver past the deadline, a day later or so (24 hours, I suppose), Fiverr sent me a notice telling me they noticed my order didn’t get delivered and suggested to contact the seller. I did, waited again, still no response, so, in the end, I cancelled. Seemed the seller had simply abandoned their account. In this case, I ordered directly, though, and there was never any communication with/from the seller, so if you “talked” to the seller, I’d message them and remind them of the deadline and see what they say, they might be sick or have had an accident, or something.
As you can see in the quoted text, Fiverr has taken care of that possibility by offering the buyer the option to cancel one-sidedly (if an order doesn’t get late, seller/buyer can only send a cancellation request that needs to be approved by the other party, or go through support).