Is it possible for "hackers"& bad guys 2come on here, email me & then get connected & mess my puter up etc ?

I am like so many others, scared of hackers or whatever they are called now. I do keep updated security as far as I know. What do you consider the most/best updated all over security.? I've lost 2 hard drives to viruses to the tune of mucho money. ANcient puter user :) but friendly :)