A dead grandfather in the apartment

One day after school, I decided to go and visit my girlfriend, as she was sick and couldn't make it to college. It was about 2:30. My house was across from hers, so she could always see me in the kitchen or on the balcony. I went to her place, sat down with tea, and talked for about three hours. Then I went into the bedroom to watch TV while she washed the dishes. Soon, she came into the bedroom and said that my father had already arrived home. This surprised me greatly, as my parents had gone to visit relatives and were expected to return very late.

I went out onto her balcony and froze in astonishment: I saw my grandfather, who had died seven years ago, walking around my apartment. I stared at him, dumbfounded, and then my girlfriend screamed in horror, realizing what was going on. After calming her down, I started getting dressed—I wanted to know what was going on in my apartment. My girlfriend begged me not to go there until my parents returned, but I managed to convince her it was nothing serious—we were just imagining things (since I don't believe in mysticism or other forms of palmistry).

Approaching my apartment, I noticed the door was open. Entering, I went into the kitchen and saw my friend on her balcony. She was waving at me, letting me know everything was okay. And suddenly, I saw her cover her mouth in terror. Then I started seeing double, my legs began to stumble, and my vision blurred. I tried to turn around but immediately fell. My neighbors, whom my girlfriend had called, brought me back to consciousness. She told me that the figure had placed its hands on my shoulders, and I had fallen.

Nothing was missing from my apartment, and the neighbors claim that no one except me entered or left during that time...