White page

Hello, today I can't access my site... I only see a white page.
I've tried to clean the DB, tried to see if there was any PHP error, tried to remove the .htacess... but nothing.
If I remove from .htaccess SetEnv PHP_VER 5.2.3 it gives me an error but if I put it and I go to my index page (like all page) I see nothing.

I haven't done any operation on my website today... and this make me worry.

I hope you can help me.

Thanks.