lightbox menu not showing on wp dashboard

Hi,
I installed and used Responsive Lightbox & Gallery whitout any problem. However, since I saved the role’s permissions in the Lightbox parameters, the lightbox menu and parameters aren(t accesible anymore in the dashboard. I only have acces to the gallery part. How can I have this acces back ? I am using User role editor as well but I don(t think the problem comes from here.
Thanks for your help !