I suspect they've been deleted from inactivity (unless you still use them today). Stealing copyrighted music was illegal way back in the mid90's so... your assumption is a bit off.
You probably won't have any problem legally because any statutes of limitations on the illicit activity. It's however odd as we at a2k won't have any idea if your accounts have been or not been deleted. Every site has their own policies. Chances are... one or more of the sites in which you are concerned about don't even exist anymore. Making those concerns moot.