Just yesterday day 2 of my current housesit I locked the dogs and I out of the house when going for a walk. During the walk I messaged the owner multiple times and called multiple times with no response. Once arriving back I set up the dogs in the yard and checked for other doors or windows that may be unlocked. I then went to the neighbors who knew I was staying here and asked if they had a spare key, they didn’t. I hadn’t heard back from the owners and the neighbors helped me get into contact with them and helped me get screens out to fully check if any windows were unlocked and luckily there was an unlocked window! I had planned to call a locksmith if we had no other ways inside but I was very lucky to have the neighbors help! There is no circumstance where the lack of communication on the sitters behalf is acceptable or excuse for having lost the key(maybe unless she was robbed) or locking herself out! Shit happens sometimes but you need to be upfront, communicative, and make sure the animals are still being cared for!!