I rebooted my linux box and it says run 'fsck manually. But I've forgotten the root password. How do i login into single user mode from grub?
Plz advice.

Hey, you can't just "log" into single user mode from grub. At least that is what I gather. Grub can manually launch your Linux distro, but its the linux stuff, not grub, that is affected. I'm a noob, so in your situation, I would reinstall Linux. Of course, if you have stuff you want to save, use a recover floppy and dump your info onto floppy or nother hard drive. Hope this helps....

Also, if it is a Grub error, is it stage one or two. I think if it is a boot up error, it is stage two. If your OS is the problem, I'd reinstall it. Then you can reset the root password.

At the selection menu, highlight the linux entry.
Type e
arrow down to the line which starts with kernel
Type e
go to the end of the line and space over one space
Type init 1 and press the enter key
Type b to boot up in that mode ( single user / init 1 )

When you get to the prompt, you can change the root password with the passwd command.

When you are done, no need to reboot, just type init 5

or at GRUB you select a to append kernel args and type ' single' at the end of the line the boot.

PeterJ

Actually, you can boot into 'single -user mode' from GRUB and LILO (and probably others). Single user mode is useful in cases like this where the owner has forgotten the root password. The password set during single user mode becomes the root password. More on single user mode:

http://www.linuxgeek.net/beginners/node80.html

and

http://www.faqs.org/docs/linux_admin/x2179.html