Disk will not mount, but shows up on System Profiler
By SSD and HDD combo do you mean something like a Seagate Momentus?

I'm really confused by you saying that the disk failed (how did it fail?) but then you have connected it by USB and you expect it to work?

The report you posted doesn't show a 

Content:    Apple_HFS


as you might expect to see under Volumes, so it appears to have been corrupted.

If data on this volume is vital and you don't mind spending money to get it back then unplug it right away and take it to a professional recovery service. 

If it would be just "nice to have back" then you could try using the First Aid tab of Disk Utility, and see if it can recover the partition(s).