As there is no ping response, I'm going to hazard a guess that you have a hung or a crashed OS. I'm going to assume, for the moment, that the display isn't showing you that the OS crashed and that the kernel has entered the debugger
ddb(4). While you can't see if this is the case, you may be able to type ddb commands from the keyboard. If not, perhaps the kernel is hung but may still respond to keystrokes -- if so, you could force entry into ddb with Ctrl-Alt-ESC. From there you may be able to
reboot 0x100 to obtain a core dump and use it to perhaps find out what happened. All blindly, of course, as you can't see your console.
You could set up a serial console, if you have appropriate hardware.
I'm sorry my advice is so generic, but based on the little I know so far this is my best guess for you to find out more about the problem. When you're able to, I recommend posting at least a dmesg and the X log.