Rhel5 cannot go to the desktop. It seems to be twm. What should I do?

Rhel5 cannot go to the desktop. It seems to be twm. What should I do? -- Linux general technology-Linux technology and application information. For details, refer to the following section. [I = s] This post was last edited by accpfirewindboy at, 2011-9-16

My rhel5 has jdk7 installed, and I changed the/etc/profile configuration file. After adding the jdk variable, I cannot go to the desktop after I restart the machine. There is only one terminal on the screen, and the time in the upper right corner. What's more irritating is that no command can be executed in this, such as cat, vi, less, more, no such command was found. I think it should be the reason why I changed/etc/profile, and I didn't back up it. I want to edit it back, but the vi command cannot be used, so I can execute the cd command, I don't know what the problem is. Please ask someone else. Thank you.