I have read already few threads related to my problem, but no one was sufficient to solve it.

I had windows 7 in my laptop and I decided to install Ubuntu 11.04.

During the installation I split a big partition of 400gb (which only 100gb used by windows) in 2gb swap and 100gb ext4 for ubuntu. However, the 400gb partition that initially was labeled as 'type' 'ntfs', now doesn't have any type and under the field 'Used' there is written 'unknown'.

There was no way to go back to the previous state and I completed the installation. Since that I haven't been able to boot Windows 7 anymore. In the GNU GRUB, besides the Ubuntu lines, I have 2 new options:
Winfows Recovery Environment (loader) (on /dev/sda1)
Windows 7 (loader) (on /dev/sda2)

where the command for booting the second one is:
setparams 'Windows 7 (loader) (on /dev/sda2)'

insmod part_msdos
insmod ntfs
set root='(/dev/sda,msdos2)'
search --no-floppy --fs-uuid --set=root 9A .... 4B
chainloader + 1
and if I try to boot it the windows boot manager says: 'Windows failed to start. .... The boot selection failed because a required device is inaccessible'

Moreover, if I try to boot Winfows Recovery Environment (loader) (on /dev/sda1) it ends up in Acer eRecovery Management where I can only completely restore system to factory defaults (where all C: drive will be deleted). The other options are not available!!!

The situation of my disk is the following:
Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0748d562

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048    27265023    13631488   27  Unknown
/dev/sda2   *    27265024    27469823      102400    7  HPFS/NTFS
/dev/sda3        27469824   222782323    97656250   83  Linux
/dev/sda4       222783486   976771071   376993793    5  Extended
/dev/sda5       222783488   226689023     1952768   82  Linux swap / Solaris
/dev/sda6       226691072   976771071   375040000   83  Linux
Please help me!!! I really need to have windows back without loosing any file, and very soon (I need to finish my thesis).

Thank you so much,

ps. Ubuntu is running properly and I will not have my windows cd for the next 3-4 weeks.