Thats what I meant with ATTENTION...
You now have to boot with the installation cd into recovery mode or such
or you have to use a live cd to reach a console:
download the iso image e.g. from www.grml.org
insert, reboot, boot from cd
you will end with a linux terminal.
type mount /media/hda1
(or mount /mnt/hda1
, depending on the live cd)
type vi /media/hda1/boot/lilo.conf
to revert the changes you made
(or use any other editor you are familiar in)
save the file, exit the editor and type reboot
eject cd, your old kernel should boot again.
When both kernels dislike sd1, it seems you are good with hda1, but missing the support for your root filesystem.
check if ext2 (or ext3 or whatever you use, see "mount" when running with the old kernel) and the partition support is compiled in.
For the FS support:
File systems --> <*> second extended fs support,
File systems --> <*> Ext3 journalling file system support
you can safely enable both.
For the partition table support:
either disable the advanced selection if you don't need it:
File systems --> Partition Types --> [ ] Advanced partition selection
or ensure that your type, usually DOS partition tables, is enabled:
File systems --> Partition Types -->[*] Advanced partition selection -->[*] PC BIOS (MSDOS partition tables) support
again, compiling as modules [M] does NOT work here.