It's possible the stations you have in your area
have switched from UHF to VHF or vise-versa
I had the same problem and have lost one channel completely
You didn't clarify if your using an antenna or
cable qam so I assumed you are using antenna.
Youll need to check your antenna to see if it
supports both UHF vhf if it only supports one
that could be your problem .
go to
antennaweb.org it will help you determine
what stations are avalible to you .