Help My phone is essentially a paperweight


It worked fine yesterday and I woke up this morning to nothing.
By that I mean, I can't make or get calls, texts, get on the web, all of my countdown tickers are reset...
Where the 3G/Service bars usually are, there's a blue circle with a slash through it (like a no smoking sign).
When I go into About Phone, everything says Unknown. It says unknown for the phone number, MIN, PRL and ERI version, mobile network type, and just about everything else. The only thing that it knows is it's own model number (SCH-I500) and the firmware version 2.2.1 (AFTER I tried the facotry reset to fix it).

When I try to make a call, a pop up comes up saying: Not registered on Network. What's going on? :(