Can your contacts be hacked and sent as email spam

Question

I have received confirmation of spam email sent from my contact list on my pc, my mail address is hosted by AOL is there any software to check if i have in spambots hidden in my system or is it within AOL servers.

Answer 1

It was your use of the term PC that led me to believe you were using a Windows computer. While Macs are technically personal computers, PC is more generally thought of as a Windows computer while Apple computers are Macs.
My confusion aside, it is still extremely unlikely your Mac is infected with some form of malware. The odds are it is a PC belonging to someone you correspond with that is infected. They are in all likelihood not using your AOL account, instead setting up an SMTP server on the infected PC and spoofing to appear as if the traffic were coming through AOL. So changing your AOL password wouldn't hurt anything, it is unlikely to help.
There is one possibility where your Mac is involved and that would be if someone else has physical access to your Mac. In that case all bets are off. If someone with ill intentions has physical access to your Mac and a modicum of knowledge, they own you and your computer. Your best protection in that case is to encrypt your entire HD using Filevault (System Preferences > Security & Privace > Filevault.)
WARNING: If you use Filevault and forget your password you are toast.