I get a message that the Task Manager has been disabled by the Administrator.
Have not found any method to get Task Manager back up.
If it was working before, this issue is usually caused by malicious
software that has changed your system settings to prevent you from
running Task Manager (and probably other programs) that would allow
you to detect and remove it.
It makes the most sense to try to remove any malicious software first,
then resolve any remaining issues when your system is clean - not try
to merely get TM to work and potentially leave malicious software
still on your system.
If you get TM to run using Group Policy Editor, regedit or some quick
fix, you may get TM working again but have not removed the malicious
software.
Perform some scans for malicious software first, then fix any
remaining issues:
Download, install, update and do a full scan with these free malware
detection programs:
Malwarebytes (MBAM):
http://malwarebytes.org/
SUPERAntiSpyware: (SAS):
http://www.superantispyware.com/
They can be uninstalled later if desired.