I don't know why suddenly the battery icon disappears from the taskbar and the System Icons settings page is displaying that option as disabled:
Can anyone help me please. How can I get back the battery icon?
try this brother,
In the Device Manager, expand Batteries. Right-click on Microsoft AC Adapter entry and click Uninstall button. Click OK button when you see the warning message to continue uninstalling the driver.
Next, click on Action menu and then click Scan for hardware changes option to restore the missing battery icon.
UPDATE
Go to start and type in gpedit.msc and press enter.
Navigate to expand User Configuration -> Administrative Templates -> Start Menu and Taskbar and disable "Remove the battery meter".
restart