Olevia 537 - wont select HD channels

Question

Olevia 537
Cable using built in tuner.
I have always been able to select HD channels (ex. 1-1,1-4,1-6 ect)
When I key in the HD channels the tv doesnt repond. If I use the channel up or down button the volume cuts off but it doent show mute.
When this first started happening I could power off and then on a few times until I could press the channel up button and it would scroll through the channels. For the last month every time I press the channel up button the volume just cuts off. (not mute because mute displays mute)
Any help will be appreciated.