problem uploading images

I have suddenly encountered problems uploading photos to my blog – I have not had problems before, haven’t changed anything on the camera and photos from camera load onto my computer OK. I’ve tried inserting directly into the blog using both browser and flash uploader and also storing in the media library.
I get this message:
The uploaded file could not be moved to /var/www/vhosts/greengardendesign.co.uk/httpdocs/blog/wp-content/uploads.
Help please! I’m a complete technophobe so please reply in non techno language!
thanks