Yamaha Audio Driver corrupt

All, I am using a Yamaha MOX8 keyboard workstation along with Cubase to produce music. Up until around three weeks ago all was well, until all of a sudden Cubase Elements 8 no longer recognized an audio card. I tried using the Yamaha software to uninstall and reinstall the MIDI driver (which also appears to be corrupted since I cannot play VSTs from the MOX8) with no luck. Then I checked in System Preferences under Audio and the sound driver Yamaha MOX6/MOX8 no longer appears there either. So, the Mac is where the problem is (or rather the corrupted software on the Mac).

I backup using Time Machine as well as offline backup. What is my best course of action in removing all components of the corrupt drivers so that I can reinstall the new drivers (the new drivers supposedly work with El Capitan, which I installed AFTER the problem began)?

Thanks for bringing your collective brainpower towards helping me go back to producing music. I appreciate it.

Best Regards,
Jeff