Flashing Folder on Start Up

[ro shriver]

Hi

I  have a Quicksilver 867 with Systems 9 and X. 
Earlier today, after having been in X, I shut the
computer down.
I just restarted the computer, and System 9 started up
instead of X.  I had not changed the startup disk when
I shut down earlier.
So, without much delay, I merely pushed the reset
button while holding the X key to boot back into X
where I wanted to be.
Now, all I get is a flashing folder icon with a
question mark alternating with the happy face.

I have Disk Warrior, but unfortunately my superdrive
does not work and I have been working with an external
cd player, which will not allow me to boot from the
Disk Warrior cd (I don't know why).

Any ideas about how I can begin to figure out what has
happened here?

Thanks,

Ro