Bluetooth Not Available - Mid 2010 Macbook Pro
I reviewed a similar problem with the same model on the MacRumors forum and the original poster responded that it was definitely a hardware issue. In researching parts to see if you could fix this yourself -- in case you are out of warranty -- I found that the Bluetooth hardware is part of the display assembly. This means you'll need to replace your display. The part itself is about $500 at iFixIt and the fix is consider "difficult."

The only other suggestion I saw mentioned was to re-install OS X, but I would lean toward a hardware issue.

Good luck!