The HD feeds are not on the same transponder, most of the HD feed come from 129, not 119. What channels have you lost? Can you go to the channel directly? What does you point dish screen show?
Just checked and the missing SD channels are back. It seemed to be all channels on 119 x13 that were out. After rechecking the charts, I realized that there are no HD channels on x13. I am getting 76 signal strength on x13 right now. If it happens again, I guess I'll call for a tech to check out the LNB.