windows xp networking not working due to security flaw

After reading about some security issues mentioned on a
well known website. A solution was offered to close one
of the ports used for microsoft networking using some dos
command I think that used net config. As promised
microsft file sharing has stopped working. How do I
restart it. I have no idea of the original command I
used, only that it used "net".

Further I can still tell windows to share folders but
other computers cannot see them. The computer is visible
on the network.

Help is appreciated, thanks