Virus threat

My phone has been infected by something named videos18+.apk. Your security system which I have relied upon for a number of years has allowed this and now it tells me it can't remove it. What is your system supposed to be able do?

i just joined the group and mysteriously someone elses email popped up in my account then switched back also it was switched to japanese and i literally had to switch it back whom can i speak to to resolve these issues