Does it work in any other application (to eliminate hardware problems).
Does it work in other worksheets?
Does it work in other workbooks?
If it works in other worksheets or other workbooks, maybe the designer turned it
off for a reason.
You should speak with the developer of that workbook.
If it doesn't work in other workbooks (and it's not a hardware problem), then
try this:
hit alt-f11 (to get to the VBE)
hit ctrl-g (to see the immediate window)
type this and hit enter:
application.commandbars("Cell").enabled = true
then back to excel to test.
If that didn't work, try this in the VBE immediate window:
application.commandbars("Cell").reset