It appears that a reinstall is in order, at least for the C compiler.
Have you considered rebooting again? Sometimes errors will clear with a second reboot. Also, you may need to do fsck on your system. Did you have any dirty filesystems? If you reboot this will happen automagically.
Did all of your services/daemons startup after the reboot? Check to see if everything that should be running is, in fact, running. Check your /sbin/rc#.d directories to see if everything started that should have.
Do you have a backup of your system. That would be a good starting point if the other steps don't work. Please tell me you have a backup. If not, you will most likely need to reinstall. the OS.