My van stopped shifting. It still starts, but not shifting into any gears. on 2000 Oldsmobile Silhouette

My transmission has shown no signs of distress, but my van stopped shifting into gear.

Asked by for the 2000 Oldsmobile Silhouette
check connection to transmission. may be loose or dirty. review when tranny last serviced. it may be due. bring to a tranny shop for diagnostic. tranny tech. will advise.