she gave me furniture, now she says it was just a loan

New York, New York...I sublet a room in a three-bedroom apartment from a girl. She told me that she was leaving her mattress and box springs, as well as a small shelf unit. She said she did not need/want it as she was moving in with her fiancee, and I could do with it what I pleased..."keep it or throw it away." I said I'd love to have the stuff, as I didn't have much furniture. She left me the warranty cards to go with the bed.
3 months later I signed the new lease with the other roommates. Now, it's been 9 1/2 months since I moved in, and the girl claims she never gave me the stuff and wants it back. My roommates (and other friends) know that I thought the bed and shelf was mine, but she says she mentioned it to one of my roommates (who did not tell me) that she might need the stuff back. She has never contacted me previously. She claims that because she has the receipt and told her friends she could get it back, that she has enough evidence to win in court.
I am only trying to stand up for what I believe in against a person who seems to go back on her word. I thought if she left the stuff, and I signed the new lease that (especially after 9 1/2 months) the stuff should be mine--plus, she said she was giving it to me! Now, she says she will sue and do anything to get the stuff back. (I found out that she never wanted to give back the key to our apartment, so I had the locks changed.) I am quite nervous about going to court, but I don't want to give in to something which is not right. Do I have a case?

Though it is important for you to have a defense, it is more important for HER to be able to prove her claim that she never gave the property to you. See the 'burden of proof' will be on her to support her claim, if she is the one who brings the action (Plaintiff). Civil courts require that the Plaintiff be able to support her claim 'with a preponderance of the facts', meaning that she only has to swing the scale of proof off of even (balance). If she is able to prove her claim, she will probably win. However, if she is not able to prove that the property was a 'loan', or you are able to show sufficient evidence that it was a 'gift', then you will probably win. Personally, I think the 'abandonment' of the property for 9+ months, plus the transfer of warranty paperwork would seem to support your position. BTW, the fact that you signed a new lease, etc. has no relevance, since the items in question have nothing to do with the lease.

I only mentioned the lease info. because I thought that she might have more right to the stuff if I was still subleasing from her. However, I thought I should have more legal right to it if she left it, and I signed the new lease. If stuff is left in our building in vacant rooms, the super throws it away or leaves it downstairs for people to take if they like. I'm sure that's what would have happened had I not wanted it. Thank you so much for your help!