Are you unable to modify cells because they are locked? Here’s how to lock or unlock cells in Excel 2010 and 2007.
1. Select the cells you wish to modify.
2. Choose the Home tab.
3. In the Cells area, select Format > Format Cells.
4. Click the Protection tab.
4. Uncheck the box for Locked to unlock the cells. Check the box to lock them. Click OK. As the dialog box says, locking cells or hiding formulas has no effect until you protect the worksheet. You can do so under the Review tab by selecting Protect Sheet.