Ah. It makes sense to create a backup of any collaborative playlists if they're important to you. All you can try now is to use the online contact form and someone at Spotify may be able to help. If you get an automated response directing you back to the community or to the help pages, make sure to reply to it directly to speed things along.
@bbonnett - If it was recent a quick Ctrl/Cmd+z should undo the delete action.
If not, quickest way to get them restored is to get in touch via Twitter: @SpotifyCares.
You can also get in touch with the customer services team directly using the online contact form and they will be able to lend a hand.
If you get an automated email reply back directing you to the community or help pages, you need to reply directly to that email (even if its from no-reply) and one of the customer services agents will get back to you as soon as possible.