i can't install antivirus. HELPPP!!!!!!!!!

[raj_kshetri]

i can't install any antivirus on my PC.
also i can't even uninstall some softwares such as TUNE-UP.
my PC has gone too slow and functions such as "task manager" /"unhiding files options" has not been functioning.
so frens what can be the solution to this problem?
* i don't wanna format my PC and also i have no internet connection on my PC.

[Disc_Junkie]

What type of error is shown when you try to install an antivrus?