Hey there, dalmations.
Did you have any issues with that drive prior to this problem? Any unusual noises/sounds coming from the drive, slow read/write speed, freezes/hangs of your system when you try to access a files on that HDD? Does the drive even power-up, do you hear it spin or feel it vibrate when you turn on your computer
I'd suggest that you try the drive with a different SATA port and cables, to see if the same thing happens, or even better - try it with a different computer. Other than that, if the drive powers up you could try accessing it via Ubuntu Live USB/DVD, to see if it's properly recognized and if you can get to your files. Another option would be data recovery software...