The only channels that are working right now are CBS, NBC, ABC, and Fox both on HD and non-HD. However when I switch to any other channel either the sound does not work or the channel itself is unavailable. A channel that isn't available on HD however is available in non-HD but there is no sound. Has anyone experienced something similar to this, because it seems that we're having more and more issues with Fios over the past couple months and we're on our second STB after the first one broke.
Sound loss and the "currently unavailable" message are signaling troubles. Is this happening on all boxes in the house or just this one? One thing to do would be to unscrew the coax cord from the wall to the set top box to the wall outlet. Make sure the tips are straight and clean of oxidation. Screw both back on finger tight. Let us know if further help is needed.