Need help to program remote for Sharp TV

Just got new HD DVR receiver (HR24/100). Directv guys set up receiver and programmed the remote control to work with the TV (Sharp LC32SB28UT). The volume & on/off worked but I noticed the mute function was not working so I tried to reprogram the remote control to get that function to work. The remote is RC65RX.  I was unsuccessful and now can not get it back so at least the remote's TV volume & on/off functions work with my TV. I tried all the codes listed for Sharp in the manual and had over-phone tech support take me through that again and other steps that also did not work. Please help...