Need help with textures refusing to render

I have an emergency with textures. I have a fairly complex model I’ve been working on for about three weeks, and it will not display textures. At all. I can start a new project and add a material to any object, then apply a texture. Displays and renders with no problems. But in the project where I really need textures to work, all I can get to display is materials. Materials display fine. Textures simply have no effect. Can’t see them in preview, can’t see them in 3D view with Viewport Shading set to Texture, and can’t render them. Makes no difference if I select a texture that comes installed with Blender or if I add my own, no texture will display. I’m using Blender 2.73. I’m getting desperate. I don’t want to have to do all of the work I’ve done over again!

Too little information

Please supply a demo file that shows the problem