Language problem again

Ok finally (and many thanks to this forum) I am about to go live with my shop/
Yet another problem. I have two languages on my site which are english and russian.Not really sure what happened, because i haven't changed anything about languages recently, except for editing russian translation file a bit.
but hikashop has gone english though joomla's default language for the front end is set to russian.
not even sure where to look.

Are you sure that you set your front-end language (through "Control panel->Language manager->'installed - Site'") to English (United Kingdom) ?

yes I am sure i did. it is set to russian (which i need)
and the rest of joomla is in russian
also i have cleaned cookies, just in case...

That's because you didn't change your russian language file properly.
There is an error (at least) in it and it prevents joomla from parsing it.
You will have to turn on the "debug language" option of the joomla configuration and you will get the parsing errors on the translation files at the bottom of each page of your website which will help you fix your translation file.