the tab key and autoindenting

[unimatrix01]

I recently was using emacs to edit some webpages and some projects I was 
working on at my work.  I came back later and I could not utilize the 
tab key in any mode and autoindentation did not work when I edited html 
or source files.  Is there any key combination or variable that I 
possibly changed that could cause emacs to prevent the tab key from 
working and the autoindentation to stop all together?  Thank you any help.