Perhaps you need to rescan for the channel. It may have been moved.
I had a chance to check my TV this weekend.
I get WUSA no problem.
It does not appear to have moved channels.Did you lose both 9-1 and 9-3?
Where are you located?
It could be that if you are outside the normal viewing are for channel 9, they have asked for it to be removed for those viewers.
WUSA 9 reappeared this past week. I didn't do anything, but now HD 9.1 is back and everything seems fine. To @TNS_2, I did try rescanning, and that did not help.