My side sliding driver door is jammed shut all of the parts for the door seam to be working. I think its the locking device < that hold the latching bar - to keep the door latch when not all the way closed.
take door panel off and open the latch manually it should be just a bar to pull i expect there is a fault on the central locking hopefully was you open it it will work again but the cheapest way is to take off the panel and have a look its a simple mechanism
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vans.