Mac Could Not Restart After a Kernel Panic
Try to boot into recovery by holding down Cmd+R.

If your computer shipped with a Mac OS X Install disc, insert the installation disc, and restart the computer while holding the C key.

If using a Recovery partition or Internet Recovery (OS X Lion and later): When your computer finishes starting up, choose Disk Utility from the Utilities window.

If using an installation disc: Choose Disk Utility from the Installer menu.
Important: If you started from an installation disc, do not click Continue in the first screen of the Installer. If you do, you must start from the disc again to access Disk Utility.

Click the First Aid tab.

Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.

Select your OS X volume.

Click Repair. Disk Utility checks and repairs the disk.

Hopefully this might solve the issue. Otherwise I suggest backing-up your data and reinstall OSX.