It sounds like you still have a grub installed, just without the menu. You can use its command line to boot your existing distro. Press ESC or Shift, etc. to get into the grub menu. Then press
c for the command line.
Then you can just run the lines that would normally boot your machine (they're in
/boot/grub/grub.cfg normally). Something like:
grub> linux (hd0,0)/vmlinuz-3.12-1-amd64 root=/dev/mapper/Zia-root ro verbose
grub> initrd (hd0,0)/initrd.img-3.12-1-amd64
Your may need an insmod or two (possibilities include at least
gzio). Your normal grub.cfg will probably do searches by fs UUID, which is more robust, but you can just give disk numbers as above.
Once you have your machine booted, use your distro's normal way of installing grub (e.g.,