最近，相信很多使用wubi在Windows下安装Ubuntu的系统更新后无法再进入系统的问题，让人不寒而慄，有很多人为此不得不重装系统。
出现此问题的原因在于更新Ubuntu时选择更新grub组件，以至于把引导区grub破坏，这也是个不小的bug吧???
下面说说如何通过U盘启动盘来修复Ubuntu。当然，你得有个1G以上的U盘，再有，你的主板必须支持U盘启动!
首先，当然是准备一个1G以上容量的U盘，用来制作可启动U盘;
其次，到官网上下载Ubuntu desktop镜像文件。Ubuntu Desktop镜像一般700多兆，从而可以把它写到1G大的U盘上，可以从Ubuntu官网下载10.4的镜像文件。
用UltraISO将其写入U盘，制作成可启动的U盘。自作完成后重启电脑，选择从U盘启动。
由于你写入U盘的实际上是个像光盘一样的Ubuntu安装盘，所以进入U盘Ubuntu后，你可以选择不安装而直接试用体验Ubuntu，这也是本方法的关键所在，利用LiveCD，我们可以暂时进入系统，借以修复原有系统!
进入Ubuntu系统后，启动命令终端，输入如下指令，在线安装lilo和mbr：
Ubuntu@ubuntu:~$ sudo apt-get install lilo
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
mbr
Suggested packages:
lilo-doc
The following NEW packages will be installed:
lilo mbr
0 upgraded, 2 newly installed, 0 to remove and 408 not upgraded.
Need to get 413kB of archives.
After this operation, 1,315kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://mirror.bjtu.edu.cn/Ubuntu/ lucid/main mbr 1.1.10-2 [23.0kB]
Get:2 http://mirror.bjtu.edu.cn/Ubuntu/ lucid/main lilo 1:22.8-8ubuntu1 [390kB]
Fetched 413kB in 3s (124kB/s)
Preconfiguring packages ...
Selecting previously deselected package mbr.
(Reading database ... 129801 files and directories currently installed.)
Unpacking mbr (from .../archives/mbr_1.1.10-2_i386.deb) ...
Selecting previously deselected package lilo.
Unpacking lilo (from .../lilo_1%3a22.8-8Ubuntu1_i386.deb) ...
Processing triggers for man-db ...
Setting up mbr (1.1.10-2) ...
Setting up lilo (1:22.8-8Ubuntu1) ...
WARNING: kernel & initrd not found in the root directory (/vmlinuz & /initrd.img)
WARNING: Do NOT reboot or LILO may fail to boot if your kernel+initrd is large.
WARNING: Please read /usr/share/doc/lilo/README.Debian
Ubuntu@ubuntu:~$
安装过程中，会得到如下lilo的配置提示，按OK就行了：
Package configuration
┌───────────────────────────┤ Configuring lilo ├────────────────────────────┐
│ │
│ LILO configuration │
│ │
│ It seems to be your first LILO installation. It is absolutely necessary │
│ to run liloconfig(8) when you complete this process and execute │
│ /sbin/lilo after this. │
│ │
│ LILO won't work if you don't do this. │
│ │
│ │
│ │
└───────────────────────────────────────────────────────────────────────────┘
然后使用lilo修复系统：
Ubuntu@ubuntu:~$ sudo lilo -M /dev/sda mbr
Backup copy of /dev/sda in /boot/boot.0800
The Master Boot Record of /dev/sda has been updated.
Ubuntu@ubuntu:~$
修复完成，重启系统：
Ubuntu@ubuntu:~$ sudo -s -H
root@Ubuntu:/home/ubuntu# reboot
OK了，相信重启后选择进入系统的画面就出现了，是不是很简单?