You can d/load LW Basic(free) version from here:
http://www.limewire.com/english/content/download.shtml
If you had the Pro version and it's still within 6 months since you purchased it, enter your e-mail here:
http://sales.limewire.com/support/pro_lookup.php, and it'll take you to your personal download page.
If it's past 6 months, you'll have to purchase it again. You should be able to get it at a reduced rate(USD$14.50) by going to your Personal d/load page.
Next time back it up onto a disc.