Renault espace Auto will not reverse!!!! HELP PLEASE?

Hope someone can help, i have a 16v 2.0 espace yesterday reverse was fine, but today it will not work, gear selector is fine as are drive, but you can feel it take up reverse position but no movement, it will even roll forward, if i rev high it will gradually move backwords and slowly gets faster, but no chance going up incline, can anyone tell me any options or how bad.
Much appreciated
Doug