busybox v1.15.3 (ubuntu 1:1.13.3-1ubuntu1)built_in shell(ash)

I couldn't do anything else. I don't want to loose my not backed up info.
I googled the error and I found that I could boot from a live cd so I downloaded Ubuntu 10.10 and boot it from livecd... Now I am running firefox from livecd trying to fix this error.

How to resolv :

Simple ways is :
It looks like it's not detecting your root partition (/dev/sda1), which is the partition that essentially contains your OS. (/)
The reason you can't input anything probably is because the console isn't loaded yet. (initramfs) somehow doesn't seem a proper console prefix to me but I might be wrong, you might want to give it some time to load.
However, I find it hard to believe that just a CUPS (Common Unix Printing System) update could cause this since CUPS is just the Linux print service.
When you boot your computer, the GRUB bootloader should give you a choice which kernel to use. See if there is a kernel that has a lower version than the one selected and see it that boots.
If it does, the kernel entry is probably faulty and won't load the proper drivers/modules for it to find your hard drive. Creating a new entry or rebuilding your kernel might work.
If that doesn't work, you might want to boot Ubuntu into recovery mode and see if you can access /dev/sda1 from there.

1.) Restart computer with a live-Cd.
Open a terminal window.
At the command prompt, write:
sudo fsck -f /dev/sd??
You must change "sd??" to something else(with ur own partition)

or u can use :

2.)When you turn on the computer, hold down the SHIFT key and the grub menu should show. Then select an older kernel.
Or boot the live CD and download and run the bootinfoscript and post the output here.
While you're figuring out the bootinfoscript you can give us the output of
Code:
fdisk -l
and
Code:
ls /boot

or u can read tis articles :

3)grub or grub2

4.) Extrass from others sites :

Recently I messed up GRUB boot loader in my laptop installed with Ubuntu which resulted in grub rescue prompt. So I had to boot Ubuntu Live CD to get it fixed. Thought of blogging it, may be useful for some one.

This fix involves two steps. First one is to chroot into Ubuntu installation partition. Second one is to install the grub MBR (Master Boot Record). I am using Ubuntu Lucid 10.04 and Live CD also of same.

Step-1: Boot your machine with Ubuntu Live CD and select Trying Ubuntu without installation option when it is prompted (Live CD mode)

Step-2: Be patient till you get complete desktop ready.

Step-3: Ubuntu main menu -> Places -> Home Folder -> Look for other partitions listed on left hand side pane. Mount one by one and identify your Ubuntu root partition. When you are in your root partition, press Ctrl+L to view the complete mount path. Press Ctrl+C to copy this path. This path is normally /media/xx..xx kind of long path, where xx..xx denotes your hard disk partition unique id.

If you know your Ubuntu root partition you can replace the above GUI step-3 with simple mount command like this (Applications -> Accessories -> Terminal):

$ sudo mount /dev/sdax /mnt/myroot (where sdax is your root partition)

Let’s say you have mounted root partition at /media/xx..xx.

Step-4: $ Run the terminal through Applications -> Accessories -> Terminal.

Step-5: Run the following commands to export the pesudo file system of Live CD to your would be root file system soon.

$ sudo mount ‐‐bind /dev /media/xx..xx/dev

$ sudo mount ‐‐bind /proc /media/xx..xx/proc

$ sudo mount ‐‐bind /sys /media/xx..xx/sys

Step-6: Changing the root file system of live system to your hard disk installed root file system.

$ sudo chroot /media/xx..xx

Step-7: Installing GRUB Boot record in Master Boot record of your hard disk. My hard disk is sda. Replace your hard disk device node in the following command.

$ sudo grub-install /dev/sda

Step-8: Reboot the Live Ubuntu. Eject the CD.