I have not used my CNC for over seven months. It worked fine before; however, I recently powered it back up, and now the X-axis only moves in the negative direction, even when I press the right arrow key. 

then probably, for whatever reason, you have lost the 'direction' signal from your motion card to either your stepper or servo. The 'step' signal is ok since its moving. It only goes in one direction because the direction is either always active or always inactive depending on how everything is wired. I'd check the connections first. After that the best method at this point is simply use a VOM to check the status of the direction signal on the motion card. It should remain in whatever state the last command (+ or -) was. And you should post what your setup is also. Bob