First install the drivers for the phone then connect the phone to computer through USB. If you have Android higher than 2.3 then the phone will appear in My Computer. Open My Computer and press ALT to enable the menu then navigate to Tools > Folder Options > View > Show hidden files, folder and drives. Go back to computer and then you can browse the phone's content, including your hidden vault.
Note that if the vault was protected and files were encrypted, then there is not way to recover them.