landlady not returning deposit

[Sandra Shaji]

Hi,I am a student just graduated from school residing at NJ.My landlady gave me a notice of 30 days to vacate the house.We I meant me and my roomates vacated the same.I messaged her too that I have vacated the place and also cleaned it,when I asked about the security deposit she is not responding on the same.And she has not taken the keys from us.What should I do,its really a big amount she has with her.