power icon from the task bar is missing

1. Click Start.
   In the Start Search field, type regedit.exe and then press Enter.
   If you are prompted for an administrator password or for confirmation, type the password, or click Allow.
2. Locate and then click the following registry subkey:
   HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify
3. In the Details pane, click the IconStreams registry entry.
4. On the Edit menu, click Delete, and then click Yes.
5. In the Details pane, click the PastIconsStream registry entry.
6. On the Edit menu, click Delete, and then click Yes.
7. Exit Registry Editor.
8. Restart the Explorer.exe process. To do these, follow these steps:
   1. Press CTRL+SHIFT+ESC.
   2. On the Processes tab in Task Manager, click the explorer.exe process, and then click End Process two times.
   3. On the File menu, click New Tasks (Run), type explorer, and then click OK.
   4. Exit Task Manager.
9. Once Explorer.exe has restarted, right click on the clock and choose "Customize Notification Icons".
10. Ensure that Power is set to "Show icon and notifications".
11. Click on "Turn system icons on or off"
12. Ensure that Power is set to "On".
13. Click on OK and close the Control Panel.

Hope that helps, have a great day!