while upgrading of windows xp sp2 to sp3 I've lost 250 gb part, ubunto operating system and many more. how should i recover the lost 250 gb part from the hard disk. it doesnt even shows that 250 gb part from the hard disk.
Sounds like corruption of the partition table. I'd suggest careful use of a disk editing tool (in the past I'd use Norton Utilities - I don't know what the current equivalent is). What you do not want to do is reset the missing partition. If you are careful, you can rebuild the partition table in-place. At that point you can see if the partition's contents are intact (good luck with that).