Go To Tools>Options ... Under Player.. uncheck the LimeWire player.
Try to launch one of your songs.. If this doesn't work...
Open Explorer and find a music file.. hold down the Shift key .. Right Click the file and choose 'Open With'... the window will pop up and you can select the player of your choice. Make sure you tick 'Open all progs of this type with this application'
(keep the shift key pressed until a selection window is opened, or it won't work)
Good Luck