OPW-00001: Unable to open password-file

Issue:

The connection to DB as "/" and "sys" as sysdba was failing with password not matching error.
When tried to reset the password using orapwd received the following error

"OPW-00001: Unable to open password-file"

Version:

DB 11.2.0.2.0
Platform: Windows 

Reason:

The reason behind "OPW-00001" is normally syntax error. We have to specify the command in the proper format.

It should be in the following syntax in windows servers

orapwd file=%ORACLE_HOME%\database\PWD%ORACLE_SID%.ora password=<PWD>

In my case I missed to specify ".ora" as part of the file name. 

ie, initially I tried with orapwd file=%ORACLE_HOME%\database\PWDorcl

Later I added .ora to file name and corrected it as

orapwd file=%ORACLE_HOME%\database\PWDorcl.ora