Best in world 0 Newbie Poster

Hi,
I was working with Luminary lm3s811 board with Stellaris Keil.
Initially it worked well..sometime later i tried to run program by changing crystal value which is normally taken as 6Mhz..
When i changed it to 6Mhz/2..it worked..but when i went for 6Mhz/12..something went wrong..
Now i can not program the board anymore..it either gives error as "no Jlink device found" or "Target DLL has been cancelled"..
I am in trouble..
How do i program board again??