(Excerpt from my post on another PC Help thread.)

"Hi! I just noticed that this thread pulled up on top of the Search Results when I looked for the solution to this problem.

I know the thread is stale, but if anyone comes across this, here's the solution to the issue:

After several failed trial attempts with Services, starting and stopping 'Remote' services, configuring exceptions on the Firewall, and enabling Solicited Remote Assistance in GPedit, I finally stumbled on the solution with the Events Viewer. Checking on the error logs on the Application section revealed that the HelpAssistant is missing or not started causing the Remote Assistance to fail.

Restart the computer. Go to Safe Mode (F8). And from there Run > sessmgr -service

This should start the program/ service again. If it fails you need to look at those things I mentioned at the start of the resolution."