Sounds like you are out of practice being social.
If there are any work colleagues you are comfortable around then try talking to them some more, find out about them, join in the office banta. If you have to talk to colleagues regularly for work purposes and there is no issue with doing so dont e-mail but get up and go to them, also keep an eye open for opportunities for general chatter, scan newspapers on their desk, if you have a radio on at work comment on news bulletins. Not only does a small amount of this show more interest in your work place which helps with job security and new opportunities in the company but the increased general social interaction will shed any loner image you might have built up and help you be smoother with the ladies.