You can turn it on with fn-f2 provided you have the correct drivers installed for your onboard bluetooth module. There used to be a great thread stickied to the top of the old Dell 17" forum before they made all of the changes around here, describing procedures and which drivers to use. Then the consensus was using the Widcomm drivers were superior to the Toshiba stack provided by Dell. Here's the thread
. Of course you don't list what OS you're running or what machine you own making this rather difficult to diagnose.
I hope this helps.