Edit: Well the characters are gone for good, but no biggie. Just curious what happened. I think maybe it was a server mishaps. I think earlier when i first log in, I mapserved and had to log out and re log in again. I'm sure due to the server rush.
Make sure you are logging into the City of Heroes client with *exactly* the same account name you used the first time. Under Paragon Chat, the client will take *any* name as valid, but the list of characters will be different for every name. Theoretically speaking, you have an infinite number of character slots, organized by however many names you can remember.
Edit: two additional notes. Account name is case sensitive: Paragon Chat brings up a different set of characters when I log in as "Arcana" and "arcana". Also, Paragon Chat may throw one more curveball at you: at one point, when I closed and reopened Paragon Chat, the default Account name that was in the box was *not* the one I had used to log into Paragon Chat, it was
my City of Heroes login name, as in the name I used to log into the real game when it was alive. Its probably stored in a reg key somewhere, and somehow it popped up. At first, I just filled in gibberish into the password blank (which Paragon Chat ignores, so you can put anything except blank) and noticed my character was gone. Took a while to figure out it wasn't logging in with the same name I first used to configure Paragon Chat.
Long story short: remember what name you use to log into the game client - i.e the Account Name blank under the City of Heroes Freedom logo in the actual game client, not the Paragon Chat XMPP login. If you forget, you'll have to extract it from the sqlite database. If you accidentally type something different, you won't get your old characters: Paragon Chat will assume you are a different player, with different character slots.