How did the drive get wiped? By your brother accidentally?
I assume the PC at one time had a legal version of Windows on it? Any you never had legal Windows 7 install discs and never made recovery CDs?
Or did he foul up your computer in some way and you deliberately wiped the drive when you used the bootleg disc to reinstall Windows and undo his foul up?
If all you have is the bootleg disk and you never had a legitimate disk, you may be hosed.
There are some ways to recover lost partitions with a boot disk. You might be able to repair or undo something with a legit Windows 7 install disc, but I would be spooked about using that fake disc any more.
Wait for more opinions.