What do I do if a dog destroys my stuff?

That's unfortunate, but Rover's insurance does not cover damage to the sitter's home or possessions. That is a cost of doing business in your home and you may be able to claim their replacement as a business deduction on your taxes. When the puppy's owner returns, you could tell them what happened. Some owners may volunteer to pay for the damages from what I've read here. In my case, the owner looked at me like I was from outer space when I told them what her dog did and didn't offer to reimburse for the damages. So don't expect anyone to pay.

For the remainder of the stay, you are going to have to be more proactive in dealing with the puppy's behavior, putting away anything it can destroy and substituting appropriate chew toys. If the dog is used to crating, then you will need to crate it while alone. Talk to the owners and find out how they have been dealing with it. Ask whether the dog has been chewing on inappropriate objects at home. Sometimes a puppy will outgrow that behavior, but otherwise, it needs behavioral training.

Good luck.

Sadly, it's one of those 'live and learn' situations. You may think your home is dog-proofed, but inevitably someone will turn up to prove you wrong. It takes a while to find all the weak points, and you'll never truly be safe from destruction unless you live in a cement box. Best you can do is discuss any destructive habits with owners, increase supervision while you're home, and your safe confinement when you're away, whether that's with crates, a "safe" room, or gated in a hallway or pen.

Rover doesn't cover damages to your items. Most puppies that I have pet sat and fostered are destructive because of their need to chew and curiosity. I tell my customers not to bring stuffed or easily destroyed toys that are important to their pup(s). Until you host the dog frequently and know it's habits, make sure you keep everything up out of their reach or in another room that you don't want destroyed. It's just like baby proofing for toddlers that get into things the second you turn your back. We all learn by our mistakes, some never to be repeated and others dog behaviors that are unexpected. Some dogs are notorious diggers so just because they are outside you still need to keep a close eye on them. Good Lucy and Have Fun with the pups!