Yes, grub gave me 3 choices, but I found that /boot was empty, so somehow all the kernels had been purged. (Incidently, the yum log said the kernels had been installed.)
I used the Rescue disk to rescue the existing system with network support, chrooted to the old system, added the DNS info directly to resolv.conf file and was able to get to external sites so that I could rerun yum. I ran 'yum remove kernel' and then 'yum install kernel' to get a new kernel loaded, which it did with an error. Then I used the rescue disk's system upgrade option to build a new loader (updating grub did not work), and was finally able to reboot.
Now, I'm missing network support, but am working to resolve that.