Lost Partition using Partition Magic

[xiaowangge]

I have a seagate 40GB hard disk and it was divided into two partitions, 20 and 20 each. The OS is installed on one of the 20G partition. I tried using partition magic 8 to merge the two 20gb partitions into one partition to create one 40gb partition retaining all the information on the 20gb partition. However when partition magic finished the 20gb partition which contained the OS became 25gb and the another one which should have been merged was still separate, and it was gone!! Partition magic says the 15gb partition is unallocated free space. Is there anything i can do to restore the missing data, on the 20gb partition? I'm using windows xp pro.

Thanks in advance.