How do I reset the postgres password for PostgreSQL on Windows?

I have installed PostgreSQL on my Windows machine for development. Now I haven't used it for a while, and have forgotten the password for user postgres (default admin user in PostgreSQL). How can I reset the password for postgres in PostgreSQL on Windows? ---- I followed Milen's suggestion, but got this message when trying to reload the configuration file: C:\Program Files\PostgreSQL\9.1\data>pg_ctl reload -D . pg_ctl: could not send reload signal (PID: 3396): Operation not permitted In Windows there is a menu option "Reload Configuration" that worked better, as shown below: