Since I have 1 tv using HDTV antenna, I would suggest if you have not moved your antenna location since last month, to rescan your channels, and see if it picks it up, some TV station disappear for me as well 11.1 CBS the following web site should show you what channels are n your area.
http
/tvlistings.zap2it.com/tvlistings/ZCGrid.do?aid=zap2it
now if you have a 15 Miles antenna, maybe you simple a) put the antenna against an outside wall of house or window, inner walls of house cause additional interferences. b) upgrade to a 50 miles antenna. if make a world of difference in picking up weaker tv signals that seems to change from week to week (ie my 11.1 CBS was like that on my 20 miles antenna got a 50 no more problem)