admin password

Hi guys and girls, can any 1 tell me how to get my password for admin as it was saved on the pc I know it but it saying incorrect?

I had a prob with this one day and checked my error_logs.  found that one of the files I edited had blank spaces at the bottom and was causing a header already sent error.  I believe it was inc/design.inc.php.  I removed the spaces and the logins started working again.