How can I access my Wubi root.disk data

Boot the Ubuntu Desktop CD, or another LiveCD or  install a new ubuntu from wubi, then mount the windows partition:

sudo mkdir /win
sudo mount /dev/sda2 /win

如果出现“Mount is denied because the NTFS volume is already exclusively opened. The volume may be already mounted, or another software may use it which could be identified for example by the help of the 'fuser' command.” 信息， 说明/dev/sda2已经挂载， 可以使用mount命令查看其挂载到哪个目录下面去了： 

e.g:  /dev/sda2 on /host type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096)   说明在我的机器上， /dev/sda2挂载在/host下。

Replace sda1 with the appropriate device (a = disk, 2 = partition number), then mount the virtual disk therein

sudo mkdir /vdisk
sudo mount -o loop /win/ubuntu/disks/root.disk /vdisk

Now the content of the virtual disk will be visible under /vdisk. 7.04 users will have to install ntfs-3g first and specify it as fstype to gain r/w access.

To check the filesystem you can use:

sudo fsck /win/ubuntu/disks/root.disk

ref:  http://blog.ibuddy.info/index.php/2011/02/how-can-i-access-my-wubi-install-via-livecd/