If you are using Windows 8 BitLocker, you need to be prepared to recovery your drive contents in the event of major issues. In an article by Jeff Bramwell, he describes the process:
With an ever-growing concern around data security, it’s no surprise that many companies (and individuals) make use of Microsoft’s BitLocker drive encryption technology. BitLocker, once enabled, will encrypt your entire drive (or drives) on your computer (e.g. desktop, laptop, or tablet). As long as your computer continues to run “normally”, things are hunky dory.
However, if you end up in a “recovery” situation with your computer, you will need a BitLocker recovery key. Not just any recovery key, but a specific key that will work only with your computer.
If you are using SkyDrive, you may already have a recovery key available.