Were they gridlines or actual cell borders? I'm betting borders. Try this:

Select all of the cells without borders and then on the Home tab, click the
down-arrow in the box just to the right of the B I U (bold italic underline)
icons, there is an option in that group for "All Borders". Click it and see
if things improve for you.

"RobIDP" wrote:

I accidently deleted a section of gridlines in Excel 2007. How do I make
them reappear? Selecting the section and activating View Gridlines doesn't
work.