How do I fix my greyed out volumes in my Seagate 4 TB external drive?

My Macbook Pro late 2007 OSX 10.6.8 is not reading a 4 TB Seagate external drive. I TB is partitioned for Carbon Copy Cloner and 3 TB contains my Music. I had issues yesterday with the Music volume appearing greyed out. After restarting via Startup Disk, the music volume appeared. I went a bit ahead of myself and tried rebooting through CCC. The system powered on with a ding, but I got this spinning grey cricle and after 45 minutes I powered off by pressing the power button for 7-10 seconds. When I powered on the Mac and plugged in the external drive, the finder wouldn't read it. Disk Utility shows both volumes greyed out, but the drive name/disk description is there. Both verify disk and repair disk say the volumes are fine. I tried switching USB cables, but nada. Please help. I have been using this external drive for the last 3 years without a problem. It's a lifetime of music from LPs, 8-tracks, tapes and CDS. Should I try Diskwarrior or TechToolPro? Thanks, Dr Saxena