You said you installed the fonts hack therefore I assume that you have also change the standard fonts out, yes ?
If so, then try to replace the new fonts with the old ones and then reset the Kindle.
And in my opinion it's Amazon's politics that pushes people to hack their device. I'll be sure to buy my next ereader from a more openminded company cause this is just silly in my opinion. Most of these hacks only unlocks very basic, simple functions of the device.
Shame on you Amazon.