If your Windows 10 Time is wrong, to fix the issue you will have to see which of the following helps you: Before we start troubleshooting this issue, it would be a good idea to run the System File.
Windows 10 2 Clocks
Windows 10 Multiple Clocks On Taskbar
Show Clock On Windows 10
Another follow up. I am using the Classic Start Menu on my PCs. I have found that perhaps after one of the recent Windows 10 updates the taskbar text color changed from the white I had, to black. Since the taskbar color was very near to solid black, the black text on a black task bar looked like the clock time had disappeared. How to change the taskbar text back to white again? I finally found that by right clicking on the Start button a Settings for Classic Start Menu page opened. You should have Customized Taskbar checked. Under Taskbar Look I had selected Opaque. The next two items in the list were Taskbar color and Taskbar text color. For the Taskbar color, I selected a near black setting from the color chart which resulted in a value of 2D2D2D. I selected the near black color so I could see the task bar against the full black desktop color I like. For the Taskbar text color I selected full white, FFFFFF. Problem solved. It would have been nice if the taskbar colors selection had been in the Settings > Personalization >Taskbar section instead under the Start Menu settings.