do you get an error message like this?
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or your task manager opens than closes right away?
or just dosn't open at all?

i get that message error in the box

Ok something (Virus, malware, spyware, blah blah blah) or someone has disabled your task manager via the registry. which is hopefully an easy fix.
1) Click on Start, Run, and type REGEDIT and press Enter.
1) (Alt - no Run under Start (default for Windows Vista, Seven)) Click Windows orb, Accessories, Command Prompt, type REGEDIT and press Enter.
2) Navigate to the following branch...
"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System"
3) In the right pane, find and delete the value named DisableTaskMgr.
4) Close the registry editor, you should be able to open the Task Manager.

my pc wont open regedit

Method 1 - Enabling the Registry with VBScript

Doug Knox, a Microsoft Most Valuable Professional, has created a VBScript that enables or disables the Registry Editor based on the following location in the registry. Of course, since the registry editor is disabled, you can't change it manually, so Doug wrote a Visual Basic Script to accomplish the task.

HKey_Current_User\Software\Microsoft\Windows\CurrentVersion\Policies\System\

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If this fix didn't solve your problem, try method two shown below.


Method 2: You must login or register to view this content.


Method 3: Rename Regedit.com to Regedit.exe

Some viruses and other malware will load a regedit.com file that is many times a zero byte dummy file. Because .com files have preference over .exe files when executed if you type REGEDIT in the run line, it will run the regedit.com instead of the real regedit.exe file.

Delete the regedit.com file if its a zero byte file to restore access to REGEDIT. In some cases, such as the W32.Navidad worm, you'll need to rename the REGEDIT file to get it to work.



Method 4: Windows XP Professional and Group Policy Editor

If you have Windows XP Professional and access to an administrative user account, you could change the registry editor options in the Group Policy Editor.

Click Start, Run
Type GPEDIT.MSC and Press Enter
Go to the following location


User Configuration
Administrative Templates
System

In the Settings Window, find the option for "Prevent Access to Registry Editing Tools" and double-click on it to change.
Select Disabled or Not Configured and choose OK
Close the Group Policy Editor and restart your computer
Try opening REGEDIT again