Grub 2 does not boot Squeeze, Error 15, Need help

[Foss User <fossist@gmail.com>]

I am using Squeeze. I booted successfully many times using the
chainloaded grub2. So, I thought it would be safe to replace grub with
grub2.

So, I tried running update-from-grub-legacy but this command was not
present even while logged in as root.

So, I ran upgrade-from-grub-legacy and now I am unable to boot
Squeeze. I get this error after the computer starts.

Grub Loading, stage1.5...
Grub Loading, please wait ...
Error 15

Please help me to start my Debian