Hi, I have a lurcher approx 20 months old, neautered female and apart from pulling on the lead/jumping up/ chewing (which she seems to have grown out of now

) we have had no major problems with her.
Suddenly she has started to cry and whine at night, we haven't changed anything- still walk/biscuit/bed, but after about 20mins she starts, at first I thought she must need to go out so I got up, she wouldn't go out just lay outside our bedroom door. It took me about 10mins before I could get her back into the kitchen, where she began whining and scratching on the door. I've tried totally ignoring her but after 4 nights I'm beginning to feel tired!
Any advice please? I'm completely puzzled as to why she should have started to do this, she's healthy, eating fine etc.