Windows 10 does not contain the Hibernate option by default, and you might want to get back the power button with other features like in Windows 8/7. Hibernate mode uses the Hiberfil.sys hidden system file which is located in the root folder of the drive. If you make a disk cleanup and delete such file, the button will be disappear.
How to Enable the missing Hibernate Mode in Windows 10
Note: If you install the Windows 10 as a VHD using the Powershell script, that will cause the system can not accessing the UEFI firmware so there is no available sleep function.
Turn on the function first
* Right click on the Start menu to open the WinX menu, and select Command Prompt (Admin) option.
* Type the command:
powercfg /hibernate on
and press Enter to execute it.
By Control Panel
* From your desktop, type Power Options into the Search box and choose the top one from the results. Or say “Hey Cortana. Launch power options.” using Cortana.
* Within the Power Options section of Control Panel, click the “Choose what the power buttons do” link at the left side. If it becomes grayed out, go to the Define power buttons and turn on password protection, and click Change settings that are currently unavailable.
* Under the shutting down setting, check the Hibernate box, and click Apply > OK button to save that.
Through Registry Editor
* Press Win + R keys, type regedit and click Ok button.
* Navigate to the key below:
* In the right side pane, double-click the HibernateEnabled and change its value data from 0 to 1 for activating it.