Th adminstrator disable .the task manger

Clarifications

to enable Task manager for you. Send him/her an e-mail perhaps?

There are two ways that I have found that this can be done either by editing the registry, or by editing the group policy.

Registry:
In "HKEY_CURRENT_USER" go to "Software\Microsoft\Windows\CurrentVersion\Policies\System" find the "DisableTaskMgr" key if this key is a 1 then the taks manager is disabled. Change the value to a 0 and this should fix the problem.

Editing the group policy:
In Run type gpedit.msc, under "User Configuration" select "Administrative Templates", then select "System", then select "CTRL+ALT+DELETE" options, double-click the "Remove Task Manager" option, make sure this is set to "Disabled". If it is enabled that means the Task-Manager will not show.

Of course you will need a little of local permissions on the computer to change these. Hope this helps.