Restore invalid/missing registry keys from a working system.

Requirement: Another working computer with the same Windows Edition. On the working computer:
1.  Open Registry Editor: To do that:
  • Simultaneously press "Windows" + "R" keys to open the RUN window.
  • In "RUN" window "Open" box,  type: regedit
  • Press Enter
2. At the left pane, press the "+" sign and navigate to this subfolder:
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BITS
3. Right-click on BITS subfolder and select Export. 4. Give a name for the exported file (e.g. 'BITS') and save it to the desktop.
5. Then navigate to this subfolder:
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\wuauserv
6. Right-click on wuauserv subfolder and select Export. 7. Give a name for the exported file (e.g. 'wuauserv') and save it to the desktop. 8. Close registry editor 9. Copy the exported registry files to a USB flash drive.
On the computer that Windows Update service or BITS Service is missing (not listed). 1. Plug the USB flash drive with the exported reg files to an empty USB port. 2. Double click at the exported BITS registry file (e.g. "BITS.reg) and allow to add its information to registry. * 3. Double click at the exported wuauserv registry file (e.g."wuauserv'.reg ") and allow to add its information to registry. * * Note: If you have problems during import, then start Windows in Safe Mode and then import the key(s). 4. Restart the computer. 5. Check if Windows Update is working. Original reference: Repairwin.com