Post Office says it delivered my package, but I didn't receive it. What...?

I live in California. I checked the tracking number on a package I've been waiting for. It was to be delivered by the Post Office (USPS). The tracking data says it's already been delivered to my address. I didn't receive the package. I was home the day they say they delivered it.

I called to see if the package is at the Post Office. They say it isn't.

What else can I do?

-The package wasn't insured

Most of the time, with decent neighborhood, The carrier may leave your package at the door.

So your package may get stolen. Or they may scan in the PO. in that case, your package may show up several days later.

Next time, with a little extra if the package is really important, using the Signature Confirmation so someone has to sign for it.

There's not a lot you can do, really. The same thing's happened to me twice. I actually got one almost a year after the post office said it had originally been delivered. I think they scanned the bar code, then it got lost somehow, and they found it later... the other one I never did get, but I wasn't home the day they said it was delivered so I don't know what happened.