Finally i have found the solution the problem by myself.
This error is not due to the installation of wordpress, its all the problem ( i wouldn't say as a problem , but it may considered as security measure) . I have used the wordpress firewall plugin that monitors suspicious activities with wordpress files and skip them to make changes with files.
Being in active ( the plugin in active stage) wheneveer i try to edit the plugin from the admin panel it consider as a security infringement and it redirects to home page.
I hope that the plug-in should have more white-list options to differentiate suspicious and authorized activities.
what ever it may be finally i have found the solution to my problem after taking 5-6 hours of review on the activities of my blog ( Analysing htaccessfile,virus scan,redirect plugin, disabling , enabling various plugins installed on my blog)