Commands disappear from Tab when cursor is placed in worksheet

[Goingstrong]

I use Excel version 10. Up until this week I have been able to highlight a cell in the worksheet, select the home tab, select and execute a command. I could again highlight a cell, select another command from the home tab and execute.

A few days ago something changed. Now I have to highlight a cell in the worksheet, select the home tab, select and execute a tab and upon doing so, the tabs disappear. In order to recover the commands, I have to highlight a cell in the worksheet, select the home tab again and find the command.

How do I fix this?