My computer had a worm.32/blaster virus thing and it just went away on its own? should i be worried?

For a couple hours my computer wouldn't let me use the internet or recovery manager, or anything. There were all these error messages everytime I tried to open something and it kept having this "malware scan" and then all the sudden the virus just stopped on its own. Everything works now (obviously, I am on the internet) and all of my other programs open and there are no more "error messages" or "malware scans". Can viruses lie dormant? I am afriad to get on facebook or my email cause im afraid its going to steal my information.