Many times instead of " nasılsınız" i heard something that sound like "nasılnız" . Is this used in spoken turkish ?

People tend to "swallow" some letters when speaking such as..

ne haber>> naber

yapacağım>> yapıcam or yapçam

and nasılsınız>> nassınız(not sure about this one)

thus to answer your question, yes it very well could be a way of pronunciating it=)