I found a solution of this problem and now sharing it with all of you , may be it help someone struggling like me.

After deep research i found that the PostgreSQL 9.x uninstaller does not cleanup the registry keys in the same fashion as the 8.3 did, and the following keys remains after a complete uninstall:

- HKLM\Software\PostgreSQL

`+- HKLM\Software\PostgreSQL\Installations

`+- HKLM\Software\PostgreSQL\Services

So, in order to get the problem solved we have to delete this entries manually. Simply, Open regedit, find these entries mentioned above ,delete it , and then check.

Enjoy…

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