背景:我是win7下wubi安装ubuntu11.04的，有天用着忽然宕机后，再进入进ubuntu只能是grub命令行界面，试了冷月前辈的方法，还是不行，set root那里死活set不了，每次set完，ls出来的内容都是一样的。后来查了wubi的官网：https://wiki.ubuntu.com/WubiGuide?actio ... irect=Wubi，找到了相关的解决办法，下面是指导：
按照提示，我们可以尝试进入win7后，打开dos窗口，在你安装的ubuntu分区那里运行 chkdsk /r，然后引导应该就会重新出现的了。Cannot boot into Ubuntu
Never try to correct Wubi boot problems by reinstalling Grub2. This will prevent Windows from booting and will not fix the Wubi install.
Ubuntu cannot be booted if Windows has not been shut down cleanly, you have to clear the Windows filesystem from Windows (there is no chkdsk equivalent for Linux yet). If Wubi fails to start, boot into Windows, run chkdsk /r from Windows on the same drive where you installed Ubuntu, shutdown cleanly and then try to boot into Ubuntu again.
Note that sometimes files are moved by Windows into a hidden folder called C:\found.000. You need to have C:\ubuntu\disks\root.disk. If you do not see those, look for found.000. You need to change the Windows Explorer settings to be able to see hidden folders first, then move the files from found.000 to their original location. Sometimes the entire \ubuntu\disks directory may be recovered to \found.000 in a folder named dir0000.chk.
Make sure you did not install on a RAID array or in an encrypted disk. Also make sure you did not install using an Alternate or DVD ISO.
如果你有空的话，可以尝试把wubi安装的ubuntu迁移到独立的分区上面去，因为据说wubi安装有很多限制，比如不能很好的玩grub2的等等.......反正很多奇葩吧。wubi迁移的教程在http://ubuntuforums.org/showthread.php?t=1519354，不过我还没试过，后面折腾过再到论坛交流吧.....