hello rhazeman
i've had this issue before with both usb bluetooth from dlink and built-in bluetooth from apple. if your bluetooth is via a 3rd party usb bluetooth adapter then unplug it, reboot and plug it back in after you reach the desktop.
if you have built-in usb then simply reboot and it should come back.
if that still doesn't solve it, the the above after moving the following files to your desktop.
com.apple.Bluetooth.plist
located in ~/Library/Preferences/
com.apple.Bluetooth.00xxxxxxxxxx.plist
located in ~/Library/Preferences/ByHost/
the end of the last file will have the mac address of the device your using to connect to the internet. (most likely your built in ethernet port)