What do I do if the US State Department lost my passport I sent in?
This is very very unlikely. If I supposed this hypothetical, they will pull the info per the passport number and they can renew it. You are not obligated for anything. For personal suggestions what I do, I scan when I get the new one and before to send for renew. So, this is extra safety net for our personal satisfaction. Hope you can do next time. Good luck!