Max P. Tafferty found out how to easily reconnect a wireless Bluetooth headset to your Windows 8 computer:
- turn on your bluetooth device
 - right click the volume icon in the taskbar
 - select “playback devices”
 - right click your disconnected device in this list
 - click “connect”
 - (optional) if your computer doesn’t immediately switch from speakers to headphones, select them and hit the “set default” button at the bottom of the playback devices window.
 
Source: http://mprtech.tumblr.com/post/64311745286/reconnect-bluetooth-headphones-in-windows-8-the-easy