When I open up task manger, this message comes up "The selected task "(0)" no longer exists. to see the current task, click refresh. when i click ok this message appears "Task Scheduler service is not available. Task scheduler will attempt to reconnect to it". After this task manger doesn't work, note these massages appear up 3-4 times each before I can acutely use task manger. What should I do?

Reboot your machine and try again, looks like a simple glitch.

I have restarted my machine many times, its not a simple glitch

In that case run a system restore back before this started happening.

System restore did not work