Restore CDs failed. Cannot reboot

I spent an entire week on the phone with support  over a problem that was never solved and now I have an even worse problem:

I have a Dimension 2400 with XP Home OS received on October 15, 2003 (refurbished)

One of the techs sent me 4 cd's that were supposed to restore my computer to the way it was when it left the factory.

Using the 1st cd, I got an error message "image file is invalid or corrupted". Next I was taken to a screen that looks like a Dos screen. The instruction was to eject the Cd and reboot my computer.  I did eject the CD but  could not reboot. I tried ctrl/alt/delete but that did not work so I called support. The tech didn't seem to know any more than I do.  He could not help me and when I asked for better help, he put me back into the que!

I found myself getting too upset over everything, and then I found this forum. It would seem that the better tech assistants are on the forum, not on the phone! So I'm appealing to the generosity of other forum members to try and get my computer booted back to XP.  The page that comes up when I boot up says "press F1 to reboot".  When I press F1, it repeats the same line. I hope someone can help me.

Thanks, mejco