Mac won't load, No bootable device, Keyboard not working nothing! help!

Hello! I need some help here....

I tried to bootcamp my Mac so I can run windows 7 and Mac OS X together

Followed instructions... Put the USB boot drive in..

Didn't recognice Drivers so I decided to start again and cancelled. (my mistake obviously!)

Now it is saying No Bootable Device - Press any key to continue, the keyboard will not work, it won't do anything! help!

Any advice on how where to start?

Martin