A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
You've accidentally changed the Preference setting in Excel> Preferences - Calculation to Manual rather than Automatic -- rather simple to do since it has been added to the Ribbon, itself :-)
Do either of the following;
- Go to Excel> Preferences - Calculation & select the Automatic option, or
- On the Formulas tab> Calculation group, click the Settings button & choose Calculate Automatically, or
- Leave the setting as it is if you prefer & use the keyboard shortcut Command+= (or the buttons in that same Calculation group )when you want to recalculate the workbook