Modify password with disk, but not keychain

Hello,
I changed my pass word with installer disk , then when I restart my new password cannot be accepted. I had warning that keychain password will not be changed., when i reset my password.
so i think this is the reason,But now, I do not know how to change or find setting of Keychain as i cannot go on the hard drive. When I restart I only get the screen to login, or else i can only get installer with pressing c-key, but here I also do not find any to reset or delete keychanin..

Please please help me!

(I have mac mini with 10.5 )