KDM doesn't start, & I can't re-assign GDM as KDM doesn't start
Dear Experts,
I seem to be in serious trouble and I do not want to reinstall Fedora OS.
I changed GDM to KDM by typing the command "system-switch-displaymanager kdm" in terminal (without the two symbols of "). At first I was told by the OS that KDM wasn't there. I installed KDM and typed that command again. This time I was told by the OS that GDM was changed to KDM. I restarted the OS eagerly. I didn't know this change of display manager was going to make me sad rather than happy.
What happens is that KDM doesn't start at all. I can't boot into Fedora with my username and password. The OS starts and the process stops at the point where the following line gets displayed on the screen (as the last line of a long sequence of lines):
started hostname service .... pt Dispatcher Service .... SEC.dmeventd or progress polling ....
I can only power off the CPU at this point. No command works at this point. No next line ever appears.
What should I do now? I understand that all I need to do is to run as superuser the command "system-switch-displaymanager gdm" but I can't do that unless I get to log in somewhere first with my username and password, and then start the terminal.