Try this ...
In the run menu type control userpasswords2
Just press WIN + R
to get the RUN menu.
The user accounts windows will now open up.
Look for the option saying " Users must enter a user name and password to use this computer
" and uncheck this option and press "OK".
Now a windows opens up asking you to enter the current password you use to log in to Windows 7. Enter the password and confirm. Done!.
This will reset you system to automatic logon!