I apologize if I am mistaken here, but something doesn’t sound “OK”.

Are you sure Avast’s tray icon is the one with a RED “X”. Or is it the Windows Security Center (or “Action Center”)?

Or maybe you “think” Avast is still installed? We are seeing some reports of several AV tools being replaced by some “enhanced security mode” issue, which is not a real AV, it is shown in RED with an “X” over the tray area, and the previous AV was uninstalled by this (without the user approval, of course). I don’t really think this is your case, but you should confirm this.

I’m not trying to confuse anyone, but the description was not clearly pointing to Avast; at least I am not so sure.

According to your next answer (Windows Security Center or something else), we may help you better.