This is a foreign language film, possibly Korean.
I can remember a couple of scenes, hope they are from the same film and I'm not merging two different films together.
It centres around a lady who moved into an apartment block. The neighbours have recently lost their son, and I remember they have some kind of temple/memorial outside their apartment. At one point in the film this lady sees the young boy outside the family apartment, he runs off and jumps out of a window.
Another scene is set the elevator. The lady is travelling in the elevator when she becomes aware of an old man standing behind her. The camera shows that this man is actually floating, there is a shot of his feet clearly being off the floor, he looks corpse-like. He floats over towards her. I don't remember what happens next.
I probably saw this 6-10 years ago.