|Without knowing what version your on, |
for Excel 2007
On the Ribbon,
Select the View Tab
Check the Gridlines box
Click the Microsoft Office button
Click on the Excel Options button to bring up the Excel Options dialog box (at the bottom of window)
Click on the Advance button in the left hand pane
In the right side pane, Scroll down to the section: Display options for this worksheet.
Check the box: Show Gridlines
You can also choose a color if you wish using the dropdown box.