Partition missing

Ok so recently I moved form Xp to Windows 7 and had 3 partitions. I formatted the partition that held windows and left the other two intact. On first boot up everything worked fine but on second boot up, one of the partitions was missing in explorer. Now the windows 7 disk management shows the partition missing with no info (pic):

http://img689.imageshack.us/i/capturegyd.png/

But Partition Master by Easus shows this:

http://img340.imageshack.us/i/capture2le.png/

I figured that the partition wasn't showing because there was no drive letter assigned but neither partition master nor disk management lets me assign a drive letter. In partition master, I can view the contents of the missing partition so I do not think it has been deleted.

Any help please?

Thank you.

 

This may help.

http://findandmount.com/