You can go here to file a lost/delayed mail claim:
https://www.usps.com/help/claims.htmIf you didn't have insurance, I'm not sure if you can do it online, but the 800# people can help file a lost mail claim too. I can only imagine how long you'd need to wait to speak with a person this week! When you do call, only say 'customer service', say nothing else and expect to repeat your self as least 12-25 times (really!).
I just filed a lost mail claim for a package that hadn't been updated in 4-5 days from the 'picked up' stage. It was magically delivered today.