What to do when Mac Update makes Excel useless?

What to do when Mac Update makes Excel useless?

1. Close and quit all programs

• Go to the Apple menu and click Force Quit
• Select all the apps in the menu for Force Quit Applications window that opens up.  (You can’t quit Finder)
• Click on Force Quit

• Repeat the steps above until all the active apps are closed

2. Remove all Excel Preferences

• Close and quit all Microsoft Office for Mac programs following the steps above.
• Click on the Go menu and click Home
• Open the Library. (Note if the Library folder is hidden, hold down the OPTION key while clicking on the Go menu. 
• Open the Preferences folder and click on the View button, click Arrange by Name. 
• When you have arranged it by name, look for a file that is named com.microsoft.Excel.plist. 
• When you find this file, click on it and then drag and drop the file to the Desktop.
• When the file is on your desktop, restart Excel, and see if you still get the same problem.
• If your error seems to be fixed, move the com.microsoft.Excel.plist file to the recycle bin. 
• If the problem is still there, quit Excel, and move the file to its original location, and follow the further steps below.
• Close all Microsoft Office apps if any are open. 
• Click on the Go menu, and click Home
• Open the Library and go to the preferences folder 
• Click on the Microsoft Folder to open it. 
• Open the Office folder. 
• Click on the file that is called Excel Toolbars (12) or Microsoft Excel Toolbars and move it to the desktop. 
• When the file is on the desktop, start Microsoft Excel, and see if the problem still exists.
• If the error is still there, quite Microsoft Excel and move the file back to the original place and follow the steps below.
• If the problem is fixed, move the toolbars file to the recycle bin. 

3. Perform a clean boot by following the steps below:

• Shut down and restart your computer.
• While the computer restarts and you hear the startup tone, hold down the Shift button.
• Let go of the Shift button when you see the Apple logo on the screen.
• Wait (this can take a few minutes to start up) and do not restart the computer again.
• On the logon window, you will see Safe Boot mode
• Press the Shift Key
• Once the computer has booted, try and start Excel again to see if the problem is fixed.
• If the error is still there, follow the steps below.

4. Use Repair Disk Permissions

• Click on the Go menu, and click on Utilities. 
• Click to start the Disk Utility program. 
• Click on the main hard disk drive for your computer. 
• Click on the First Aid tab. 
• Click on Repair Disk Permissions.