You can unhide the calculation sheets form settings. Please follow the below steps to hide/unhode sheets.

  1. Goto Settings
  2. Goto Navigation Options
  3. Choose Hide Calculation sheets option as  NO
  4. And Apply the settings

 

 

Alternatively, you can unhide calculation sheets as shown below:

  1. Right Click on the Sheet tabs
  2. click on the Unhide command
  3. Choose choose the sheet to unhide
  4. And press OK