Recently my computer broke down and the Linux Ubuntu 10.04 partition could not be loaded back. What should be done to recover it back? What could be the possible error?
Boot from a "rescue" disk or just a live CD and run fsck on all of your partitions.
To do fsck:
Type fsck partitionname in terminal
Testdisk may be helpful for you.
A video can be reached on: http://www.youtube.com/watch?v=EncqYP1ijFg&feature=player_embedded
My personal experience with lost partitions (which was fully recovered after using Testdisk) is documented in this forum.
NOTE: Testdisk will bring back any partitions you accidentally erased or lost. But some data may not come back with the partition. However, you can gain access to that data when the partition table is available again as shown in my experience documented in the forum's link I provide here.
BTW: Testdisk and useful information related can be reached clicking here: http://www.cgsecurity.org/wiki/TestDisk