Somebody can u please help me

Hello,
whenever i go and turn on my pc it says that the malware portection is turn off and i cant turn it back on but i only have one antivirus thing on my computer and i would really like to know how i fix my problem if anyone can please help me out i really need to know what is wrong with my computer because it also says in my AVG that everything is running the way its supposed to so please help me anyone