Notebook reloading Win7 system can not enter ubuntu solution

1, first open the Win7 system command prompt window, and then enter the command sudo-i;
2, first find a ubuntu installation In that partition, use the command: fdisk -l to output my part as follows:
Device Boot Start End Blocks Id System
/dev/sda1 5 69443 14998528 83 Linux
/dev/sda2 69443 94825 5482496 82 Linux Swap /Solaris
/dev/sda3 * 94825 95299 102400 7 HPFS/NTFS
/dev/sda4 95299 271531 38066176 7 HPFS/NTFS
The partition where my ubuntu10.04 root directory is located is /dev/sda1, If you are not sure, look for an id of 83.
3, the root directory of the original system:
mount /dev/sda1 /mnt /dev/directory /mnt, of course, you can also choose other places.
Here to explain the directory, is to install the system is to select the root partition /resulting directory, for example, I installed the system is sda1
Enter mount /dev/sda1 /mnt here /dev/sda1 /Under mnt
It is important to note that if you mount the boot separately when you install the system, you need to add one more step
mount /dev/sda12 /mnt/boot.
sda12 is the partition where the boot is separately mounted when the system is installed.
4, grub-install --root-directory=/mnt /dev/sda
5, you will see Installation finished.No Error Reported.
6, sudo init 6 Re-system, you can choose to enter the system, if you see the grub> command line, it may be that you choose the boot partition in the third step is wrong;
7, go to this step is ok, some users said that may not be able to enter the Win7 system, also need the following steps:
sudo update-grub2 update grub2 on it.
Enter the password as prompted. If it goes well, a similar statement will appear, which means success.
Generating grub.cfg …
Found linux image: /boot/vmlinuz-2.6.32-22-generic-pae
Found initrd image: /boot/initrd.img-2.6.32-22- Generic-pae
Found memtest86+ image: /boot/memtest86+.bin
Found Windows 7 (loader) on /dev/sda3
done
After setting up as above, you can enter ubuntu. If you are reinstalling the system and encounter the same problem, you can solve it by the above method.