Excel's workbook protection features enable you to prevent changes to anything from a single cell to an entire workbook. To protect cells, objects, and scenarios, from the menu bar choose Format - Cells and then the Protection tab. First select the item's protection format. Cells, objects, or scenarios can be locked or unlocked. With the protection option on, locked cells cannot be changed.
Many options are unavailable when a worksheet is protected.
For instance cell formulas and scenarios can be hidden or visible. With the protection option on, hidden cell formulas and scenarios cannot be seen. The next step is to turn on the worksheet protection. It will also give you the option of using a password. If you forget your password, there is no way to retrieve it, and you will never be able to access your worksheet.