After reloading the system, the Ubuntu boot interface is missing and goes directly into the newly installed window system. Here's how to restore the Ubuntu boot:
1 Prepare an Ubuntu system installation disk;
2 The Ubuntu system installation disk into the CD-ROM drive, restart the computer, into the BIOS, will boot up to the CD-ROM (cd/rom) startup mode;
3 then save the settings exit, wait a moment to enter the Ubuntu installation interface, at this time there are two options
1. Try the Ubuntu system on the CD
2. Install the Ubuntu system on the computer
Select "Try Ubuntu system on this disc" and go to the Ubuntu system and open the terminal (the shortcut key combination is ctrl+alt+t);
4 Enter sudo-i under the terminal (Get Administrator privileges)
5 in the terminal input fdisk-l (is the lowercase letter ' l ', view disk characters)
A message similar to the following appears:
disk/dev/sda:320.1 GB, 320072933376 bytes
255 heads, Sectors/track, 38913 cylinders
Units = Cylinders of 16065 * 8225280 bytes
Disk identifier:0x70f7ab9c
Device Boot Start End Blocks Id System
/DEV/SDA1 1 1627 13060096 Unknown
Partition 1 does not end on cylinder boundary.
/DEV/SDA2 * 1627 1639102400 7 Hpfs/ntfs
Partition 2 does not end on cylinder boundary.
/dev/sda3 1639 8166 52429859 7 Hpfs/ntfs
/DEV/SDA4 8167 38913 246975277+ 5 Extended
/dev/sda5 8167 32385 194539082+ 7 hpfs/ntfs
/dev/sda6 32386 38788 51432066 Linux
/dev/sda7 38789 38913 1004031 Linux Swap/solaris
Then find the letter ID 83, according to the information shown above, when the fashion Ubuntu is installed in Sda6 this partition.
6 in the terminal input mount/dev/sda*/mnt
(* represents the partition where the Ubuntu system is located, that is, the partition number shown in the previous step with ID 83, as shown above in the Sda6 section,
So the input is mount/dev/sda6/mnt.
Note: There is a space behind the mount, there is a space behind the SDA6, these two spaces do not miss, otherwise will be an error.
7 After the end of the previous step, continue to enter Grub-install in the terminal--ROOT-DIRECTORY=/MNT/DEV/SDA
Wait for a while, if appear installationfinished,no error reported will say success
(Note: There is no space between Grub-install,--root Front has a space,--root front is two '-',/mnt a space behind)
8 to this, Ubuntu boot basic restore, restart the computer, you can see the familiar Ubuntu boot interface, into the Ubuntu system, open the terminal input
sudo update-grub
Wait for a moment to display the following information:
Generating grub.cfg ...
Found Linux Image:/boot/vmlinuz-2.6.31-20-generic
Found initrd Image:/boot/initrd.img-2.6.31-20-generic
Found memtest86+ Image:/boot/memtest86+.bin
Found Windows Vista (loader) on/dev/sda1
Found Windows 7 (loader) on/dev/sda2
Done
The restoration work was completed.