I did that with the same result.
Try this: Go to C:\Windows\ServiceProfiles\LocalService\AppData\Roaming\PeerNetworking and delete all of the files in this folder. Now restart the computer.
Go to Services again and you should be able to start 'Peer Networking Grouping' and 'Peer Name Resolution Protocol'. Restart the computer again.
When you log on this time, check the event log again, to ensure no errors concerning the two services are present and also check Services to ensure the two services concerned are running.
You should now have full functionality restored to your homegroup.