hard disc damage

Appreciate any help with recovering damaged hard drive:

I have a Samsung 120G HD(data drive only) which had the power pin accidentally connected the other way around causing a short circuit and frying the power pack.On replacing the power pack, the HD would not work and would short circuit the computer(no power).Once it was disconnected the computer worked fine.

ANy ideas?

Do I just need a new circuit board or have I likely lost data?