Recently, I accidently bumped the side of my computer while unplugging an adapter for my piano. The jolt destroyed the disc and I lost the hard drive. I bought a new computer and installed Sonar 7 from the DVR. It loaded fine, I can perform all the functions except for one, I can't get it to play, and the record button is dark and doesn't work. I can open the files, copy, cut, paste, do everything except get it to play or record. Have I overlooked something simple?

What interface and driver mode (i.e. WDM or ASIO)? Sounds like the driver is not installed/detected or SONAR is not configured to use the correct driver mode or I/O drivers/channels are not enabled. Check that drivers are listed and checked in Options > Audio.

this may help https://www.cakewalk.com/Support/Knowledge-Base/Audio-Hardware-Setup-Guide