Losing stairs in other meshes when joining objects I am a Newbie to Blender.

My dilemma is that l have four sets of stairs as individual objects in a scene, with various other objects and when l combine all the objects into one scene/object, the stairs are integrated into the other meshes and disappear.

Is there any way of combining the objects without losing the stairs?

Screenshots of before and after joining objects. I have applied textures using Cycles render before joining the objects, is that the problem?
They shouldn't join meshes. One object can have multiple parts. Are you in cycles or render mode? I think your problem is most likely an unapplied subdivision modifier on one object and when you join the others this affects them. To fix this apply your modifiers before you join. 
Hope this has helped.

Just a note for next time: please post either the .blend file or screenshots of the problem. That makes it a lot easier to see what's wrong.