I want to enable task manager is disabled by the virus when I enable this it is automatically disable by the virus again I want permanent solution.
The only permanent solution is to eradicate the virus.
Malwarebytes' Anti-Malware is excellent for removing viruses.
You can also use an
antivirus online scan such as ESET Online Scanner, Trend Micro House Call and Kaspersky Labs Free Virus Scan. Please note that they might require you to use Internet Explorer as your browser as an administrator, and that each scan may take several hours.
I too would recommend use of an anti-virus as a permanent solution. Though you can avoid such future problems by limiting Write Permissions to the registry key :
Note : Delete the