If you want to protect only specific cells in your excel document and the protect sheet feature is tuned on you will need to first unlock all the cells on the worksheet, lock the cells that you want to protect, and protect the worksheet.
Here is how to do it:
1. Select all of the worksheet (hold down the Ctrl key and A) or all of the working cells in your sheet (hold down the Ctrl, then select Cells).
2. When the selection has been made, right-click the mouse and select Format Cells from the drop-down window.
3. Click the Protection tab, deselect the Locked check box, and click OK.
4. Now click the specific cells that you want to protect. You can select them all at once by holding down the Ctrl button on your keyboard while you click each cell.
5. Once all cells are selected, right-click the mouse again, go to Format Cells, click the Protection tab, and this time select the Locked check box and click OK.
6. The final stage is to protect the worksheet. Click Tools, go down the menu to Protection, click Protect Sheet, then click OK. A password is optional here. If you want to password-protect it, enter a password (you will need to reenter it to confirm), then click OK. Don’t forget your password because there is no way to retrieve it.
7. Save your work!!
Now your worksheet is protected, and locked cells cannot be tampered with unless you follow step 6 to Unprotect sheet or open it with the protection password you assigned to it.