When a package says it's been delivered but you never got the package it could be that the package was delivered to the wrong address.
I've had other peoples packages delivered to my address accidentally so it does happen.
So if you haven't gotten your package maybe ask around your neighbors and see if they got a package or if not contact the UPS or whoever delivered the package.
They have GPS that can show where exactly the package was delivered too.
Also the package may have been left behind a chair, table etc on the porch and hidden out of view so check around there.
Sometimes I've had UPS put a package behind a bush and then they noted on the tracking where it was.
So now I check around the bushes just in case the driver decided to put the package there although most times the UPS places packages in front of my door.
But if you still did not get the package you should contact the shipping company who delivered the package to find out what happened.