About portable hard disk drive

Hello,
Evening.

I am using XP in my laptop and also in my PC. I have a portable hard disk drive and it is partioned. I have some important documents there . Now when I try to open my portable drive ,it is showing some portion of the drives are used and the rest are free. But I cannot see the used portion. I tried with a lot pc's and laptops but no use.

Can you please help me to solve this problem ?
With regards

sharif