material mode preview is blank

Hello,
I am new to Blender and using 2.71 version.

I am facing some problem in material mode.
I have done some changes in the settings (not sure what?) but now I can’t see any visible material or texture for the objects in the preview section. Although for previous objects, still I can see…

Can someone, help me in this please?

Regards

No blend file so we cannot see what you see !!