You should do as nixgeek suggested. Boot to the installer disk, and choose Change Password from the menu. Select your drive, and you should see your account name in the drop-down list. Note the spelling. Change your password again. Type it carefully, noting any capital letters or unusual characters. Save the changes. reboot your Mac, and enter the password at the login screen.
Final step after logging in - Change your password again through the Accounts pane in your System Preferences. That will then change your keychain password to the same as your login password.
You should then be able to change your login settings so you will have a normal login. If you normally have an automatic login, you may need to turn that off, restart, and then turn auto-login back on, which will reset that type of login.