I uninstalled AVG 2015 free version and did a system restore, the 2015 AVG is back but it will not work

i wanted to do a system restore, just go back a few days, however it would not work as it said i must disable my anti virus, i did but it still didnt work so i uninstalled it. this time the system restore work but the AVG is back. I wanted it back but it doesnt work now and if i try to reinstall it or uninstall it nothing happens. Any idea on what to do, should i do a full system restore maybe?