I'd try this first.
Use the outlining symbols to the left of the worksheet window. Click on the
highest number (should be the rightmost number) to see all the rows in all the
grouped rows.
If you can't see the outlining symbols, then use:
tools|options|view tab|check Outline Symbols
If you still have hidden rows, maybe they were just hidden manually.
Select the visible row on the top of that range through the visible cell on the
bottom of that range. Then Format|Row|Unhide.
If that still doesn't help, make sure you're not hiding rows via
Data|filter|autofilter. Try data|filter|show all.
And if that doesn't work and you're missing the rows at the top of your
worksheet, maybe you've frozen the panes so that those rows are just off the
window.
Window|Unfreeze Panes
All these menu items were in xl2003.
