Once you find the offending files and remove them, you'll need to download an AL mailbox.  Rezoning to community will put the phone and trash can on the lot, but then rezoning back to residential will remove those and not put the mailbox and trashcan in.  I've extracted both of those files for download.

The houses more than likely had a recoloured mailbox, and now there's recolours of the original mailbox in your game and those mess up the apartment mailboxes for some reason. This happened to me, and I won't even go into the horror it made me go through, but if you can find the files you downloaded, remove them, then rezone the lot like amc said. That should work and bring back your apartment mailboxes.

And whenever you download a house, use the Sims2Pack Clean Installer, and don't let the mailbox recolours in.