hello ppl,
This would really sound silly...but pls help me

I have ..or rather HAD an oracle d/b server installed on my local machine...

I rally wanted to play around with the database to learn more.
So I tried to change the prev of the SYS user.
Now its changed..now what to do?
Cause I ve lost all the prev
Is there any way to get it back........
I dont want to re install the d/b again
thanx in advance