Tried to install OS X on my external HD my computer crashed

Tried to install OS X Disc 1 (which I believe was of 10.5 Leopard) on my external my computer crashed. I can't recover it. The hear the chim when it switches on but the screen is perminently white with no graphic or loading icon.

Here is what I did whilst running on Lion on my mid 2009 MPB:

1. Inserted the grey colour OS X Disc 1
2. Opened System Preferences
3. Selected the CD and clicked Restart
4. The MBP "restarted"
5. It stayed on this white screen for while a tapped a few keys and the mouse but nothing. (I hope tapping the keys mouse didn't cause anything bad to happen).
6. So I turnned it off and on again with the power button,. the same white screen issue

😟

I could really do with some help on this, I use my computer I great deal and need for important things such as work. Thanks.