Messed with my harddrive. Mac doesnt boot

Hi

I was trying to boot a new OS off an external hard drive but i think i formatted my main hard drive as journaled. now my mac doesnt boot and i get a kernel panic when i start it up.

can i unjournal my hard drive? im pretty clueless on the whole situation....
if you need anymore information please ask and ill tell you whatever i can.
or If anyone could GMAIL chat me at [email protected] That would be awesome.

I reinstalled my mac OS. Now i have previous systems in my macintosh hard drive can i restore it? i hate having a fresh start... i want my old mac feeling back!

i feel stupid haha. what do i do now?

Too late now. Your old system is in a folder along with whatever data and documents you had. Your applications will have to be reinstalled. So, in effect you're starting over.

Next time, make sure you have a backup. Since you have an external hard drive, use it to make backups with Time Machine.

Regards.