My boyfriends son downloaded a bunch of songs on my computer, now all his crap is coming up on my library. I only had 41 songs there, so how do I delete EVERYTHING and just start again?

Find your saved folder. In LW tools > options > saving shows you the location. If you go to LW's library, click on Saved Files then click Explore...your saved folder will open for you. Delete what you don't want & you won't see it any more

You can also delete from LW's library directly (right click > delete). Files deleted this way don't go to the recycle bin (unless you use 4.13.0 beta). So you have to be careful that you don't accidentally delete files that you want to keep...it's probably safer deleting from the saved folder.