Visual and Code Tabs Missing

I have WordPress installed on 2 domains. One is version 2.1 and the other is 2.2

Before when I went to write a page or a post I had 2 tabs, one for Visual and one for Code.

These tabs are missing from both of my blog domains. Is there something I need to check for these tabs to appear. I have looked and looked and have not found anything I can check mark so these tabs will appear.

What do I do…..please help

Debbie