Yes, I was descheduled last May. All I can say is "Good Luck".
You are now off the "fast track" and they'll get around to rescheduling your appointment when they get around to it (who knows when).
My suggestion:
1) Wait a month or six weeks (to make sure they don't quickly reschedule it), then...
2) Take an InfoPass appointment and find out exactly what happened. If it is name check, you are pretty much out of luck for a while (it seems).
3) If it's not name check, contact your congressman and your senators (hopefully at least one of your incumbants will have won and still have an office set up). They have staff dedicated to immigration issues. In my case, it was the intervention of my Senator that got my interview back on track (many months later). I tried my congressman first (he lives only about a 1/2 mile away, so I figured it was a better first try). All that did was get a staffer who phoned me back and told be everything I had found out on my own. If at first you don't succeed,... try another office holder.
When you talk to the congressional/senatorial aid, be very pleasant and polite. You want them to think you'd make a nice new citizen and that they should go out of their way to make your path smoother. If everything works, phone them back and say thanks (or, do what I did and send flowers) -- you want them to be nice to the next person as well.
If it is name check (which I never did hit <sigh/>), read up on strategies on the various threads on this board.
Things that are useless (at least in my experience)...
1) Taking additional InfoPass appointments - though having a record of doing that might be useful in the long run (and I think it helps getting sympathy from the congressman/senator's offices)
2) Writing the district office director a letter -- at least in Dallas, they go unanswered.
My PD was last September, my original interview was scheduled in May. I went to 4 infopass appointments this past summer. I sent the Dallas District director 2 unanswered letters. Finally last month, my interview was scheduled (which I had today). Check out the Dallas timeline (posted today) for my detailed timeline.
Good luck