There's two main choices you can take now. You can either add linux to the windows boot menu or you can replace the boot loader with lilo again.
You'll need some kind of floppy to load linux so you might want to load this boot floppy:
To add linux to the windows boot menu boot into linux and dd the first 512 bytes of the boot sector to a file:
dd if=/dev/hda6 of=bootsect.lnx bs=512 count=1
Copy the file to the c:\ and add a entry to the boot.ini file that looks something like:
C:\bootsect.lnx = "Linux"
To reinstall lilo just edit the /etc/lilo.conf and make sure there is an entry for each os. And then run lilo to install.
If you are doing that from the floppy do something like:
mount /dev/hdaX /mnt
mount /dev/hdaX /mnt/boot
Then edit /mnt/etc/lilo.conf
chroot /mnt /sbin/lilo