Solution:
Please follow these steps:-
1) Logon to your phpMyAdmin
2) Go to wp-options table.
3) Find & delete entries with option_name :-factory_wpsharely_plugin_activation.php 

Try to Activate plugin through wp-admin
If still its not working  follow steps 1-3 & delete following files also.

factory_wpsharely_plugin_activation.php
factory_wpsharely_plugin_viewtables
factory_wpsharely_plugin_types
factory_wpsharely_plugin_shortcodes
factory_wpsharely_plugin_metaboxes
factory_wpsharely_plugin_activation.php
factory_wpsharely_core_layouts/forms/default-controls