HELP PLEASE

I am on talk talk and accidently uninstalled part of the anti-virus , which has left it inaffective , i have tried to uninstall but it wont let me , ive tried to add AVG and it locks up computer , i have the talk talk antivirus disc but it wont update because it says its already on the computer , any ideas how i can get rid of it

thankyou in advance

If the AV uses the windows installer the Windows Installer Cleanup Utility below may help.

Quote:

With the Windows Installer CleanUp Utility, you can remove a program's Windows Installer configuration information.

You may want to remove the Windows Installer configuration information for your program if you experience installation (Setup) problems.

Link

Install the program again over the top of your current installation. That will allow you to uninstall it.