how can i fix the starter motor on my renault kangoo 865d?

This morning i started my van then realised i needed to get into the back. stopped it, used the key. Got back in. went to start and nothing. The starter motor doesn't even click. The lights do not even go dim as if there is power getting to it. It's like it's imobilised. but with no imobiliser.. Can anyone PLEASE shed some light and help?