FAQ What does unbootable volume mean?
From Computer Evolution Knowledgebase
This error comes about in all flavors. Perhaps you get a blue screen when your machine is booting into Microsoft Windows which gives UNBOOTABLE_BOOT_VOLUME errors. Perhaps your computer says Non-system disk and goes nowhere. Perhaps it gives a more terrible message like imminent disk failure, back up all data immediately and then asks you if you want to continue. Mostly it could mean the same thing.
Blue screens
A blue screen is Microsoft Window's way of saying there is something not necessarily right. They usually appear out of nowhere and show up literally as a big blue screen with white text. However, it's usually a vague way of reporting errors and whether or not it's hardware or software. For all you know there could be a bad driver making your wireless not work, or it could be that your wireless card is bad. Or maybe your hard drive is failing. Or maybe you should just run a Windows repair.
In any case, since a method of diagnosing this error is rather lengthy, I'd suggest submitting your computer to have it looked at. Just telling the technician at the other end that "it blue screens" will be sufficient.
In this case, if your computer boots up far enough that you can back up your data, I would suggest backing up your data.
Imminent disk failure and unbootable volume errors
Most likely, your hard drive is dying. In this instance, it is usually a purely hardware error, since the hard drive is considered hardware. Since the hard drive is made up of moving parts, the longer you have it running, the more damage you could be doing. You should probably power down your computer immediately, and submit it to a specialist for data recovery. If you haven't ever backed up your data perhaps this is a good lesson to start. Although now it is a bit late.
