HI, From wrodpress Install Styles option I installed a style named Facelook but after effective installation after i attempted to activate it, following message made an appearance.

The following themes are installed but incomplete. Themes must have a stylesheet and a template.
Name     Description
Facelook    The parent theme is missing. Please install the "bp-default" parent theme.

where I'm able to install british petroleum-default..?

what's happening....

Seems like the "Facelook" theme is really a child theme from the "british petroleum-default" theme. You will need to locate the british petroleum-default theme and do the installation before you use Facelook.