Your description is a little confusing, could you confirm the following? You lost the ability to read the Hard Drive but need to recover the files on it.
Is this a boot drive? How did he loose the MBR? How does the drive show in Disk Management?
If he really lost the MBR, you would not be able to see the drive's configuration, so no partitions would show. If this is the case, using something like Partition Wizard bootable version may be able to recover the partition information.