Does X come up when you log in and type startx? If so, X is functional. If not, reinstall the desktop (not the whole system).
If X works, you need to find out why it doesn't come up spontaneously. Two things I can think of:
1) no display manager. This is the program that launches X and puts up the graphical login widget. It's kdm if you're using the kde desktop but I don't know what the mate version uses; could be gdm, lightdm or slim. Check for all of them.
2) wrong default init level. Check your inittab file or post it here.
Last edited by hazel; 11-28-2016 at 02:29 AM.