Go to the Start menu, Programs>Limewire>Uninstall & choose uninstall.
If it still doesn't work, download the "Offline" installer version from here
http://www.limewire.com/english/content/download.shtml
Also, before installing, control-alt-del & open the process manager. Make sure there is no Limewire process running. If there is, force it to stop using the process manager. Then install LW.
BTW when you say you had LW for quite a while, which version were you running? If it's earlier than LW 4.4 then you will need to find the installer within the LW program folder or else, use the add/remove programs control panel. That "
only" applies to versions earlier than 4.4