Dear wd i have great problem

i have My Passport Essential 320g and i divided it to 2 partitions , my brothers use it for a time and when i try to connect the device to my laptop it not respond and the laptop ask me to format the disk , i closed the massage and removed the disk and reconnect it , , the 2 partition are appeared and i can open one but the problem is the other partition not respond to any order in spite of it’s appearance in “my computer” and my laptop become slow to some extend

i try to use programmers “HD Tune Pro and  Western Digital Data LifeGuard Diagnostics - DLGDIAG for Windows”

i have very important files on it and i dot want to lose it 


                                                                                                          please help me

What OS are the PCs using the drive and how are the partitions formatted NTFS? Are you sure your brother didn’t do something like reformat? What does it show about the drive and partitions in Disk Management?