Did you make a boot floppy during your install? Most distributions of Linux give you the opportunity to create a boot floppy during your install. This is always a good idea. Should you make a mistake like forgetting to run lilo after modifying /etc/lilo.conf a boot disk would allow you to recover and get your system back in running order.
Have you been running as root against our better advice, and removed part of your filesystem, where your kernel is? Have you installed a new kernel, and fogotten to save your old running kernel as a fallback position? All these scenarios are easier to recover from with a boot floppy.
Basically, a boot floppy, created during the install, contains a kernel, modules and ram disk that will work on your system. It contains many of the same configuration information gathered during the install. If you didn't create one during the install, don't fret, you can still create one now.