blank screen after installing plugin

Hiya,

I installed the latest version of Buddy Press on my rather old version of WordPress (I was trying to install a plug in to back up the site before installing upgrades), then after I tried to enable BB my site went blank, I can’t access it through the admin page or see it at its usual domain http://www.theoxfordretreat.com

I’ve seen other threads that suggest amending changes using FTP but (or cPress?) but until about half an hour I hadn’t even heard of these things – I’ve tried giving it a go but I can’t figure out how to get an FTP account in the first place.

Am so stuck and would really appreciate any help you can give!