How do I restore format cells menu?
 

I am working in Excel 2002, multi-page workbook. On some pages "format cell"
is not operational - neither from the toolbar or by right-clicking mouse.
Command is there but produces no result. On other pages in the same book all
is well. There are no protected pages, and this is happening only in one
particular workbook. Have tried reset to no avail. When copy and paste
material to properly functioning page problem is carried as well. Any ideas
would be muchly appreciated.