If Sanskar kidnapped Ragini then he would never let the blame go on Swara.
It's fact that he loves Swara because they showed the dream sequence. He cant be acting to love her if he dreams of kissing her on the forehead (unless CVs are being stupid again)
So it would be illogical for him to kidnap Ragini and put the blame on Swara (whom he loves)
Unless he wants Swara to feel isolated and come to him for support... but I dont think he'd play such dirty games.
Personally, I don't think it is Laksh either.. May be I'm being optimistic but I think it would be too obvious if it was Laksh... Like everyone knows he wants to get rid of Ragini.. It would just be not much of a twist.. Plus he knows Sanskaar would trust Swara so it's not a good method to separate them.