Installing postmaster at local computer

hello there again folks..

i install my postmaster service from apache but it was issuing me an error.
by running this at the cygwin command prompt:
$cygrunsrv --install postmaster --path /usr/bin/postmaster --args "-D /usr/share/postgresql/data -i" --dep ipc-daemon --termsig INT --user postgres --shutdown # [5] [6]"
...the error is:
cygrunsrv: Error installing a service: OpenService: Win32 error 1073:
The specified service already exists.

and then at services/msc i try to start the postmaster service but still has the error alert.
Could not start postmaster service on Local Computer.
Error 1069: The service did not start due to a logon failure.

How can i fix this problem? pls help..

or how can i uninstall the service and install them again so it will refresh everything..