Forgot username password of POSTGRES

Look for pg_hba.conf file in installtion directory
C:\Program Files\PostgreSQL\9.1\data\pg_hba.conf

edit this file below:
(replace md5 with trust)
# TYPE DATABASE USER ADDRESS METHOD

# IPv4 local connections:
host         all          all                127.0.0.1/32            trust
# IPv6 local connections:
host         all          all                ::1/128                     trust


restart the service

login annd enjoy