X11 in solaris

How to check whether x11 is enabled in solaris or not . we were unable to connect to one solaris box thro xwindows, please help me on this........

which version of solaris?

check /etc/ssh/sshd_config

In solaris 10, ensure the following
# X11 tunneling options
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes
then svcadm restart svc:/network/ssh

It would help if you were more specific about what you're trying to do. Are you trying to forward X11 through ssh, are you trying to connect using xdmcp, are you using VNC, and what exact error are you getting or what are the symptoms.