Why can't I change the shading of one of my objects from Wireframe to Solid? I have two objects in my scene, a boat and a seat. When I try to change the Viewport shading to Solid, the seat changes but the boat stays in Wireframe. I tried looking for an answer before posting but didn't find one.
It's a common mistake You probably selected all the faces and hit Delete->Only_Faces.  So only the vertices and edges remained on the object. 



To check if faces are missing you can go in edit mode and face select mode.
The faces it would look like this:



No faces will be like this: