I was about 12 and I was all alone in my house. My sister went to a friend's house, my parents were out and my grandparents were at a wedding in Green Bay. I was in my room on the internet searching around for good ghost stories to tell my friends.
I was in my bedroom which was at the end of the upstairs hallway next to the bathroom. If you walk out of my bedroom there is one right across from it which is a guest room and is always kept shut because one of our 3 cats likes to get in there and stay for days. Next to those two rooms at the end of the hallway is a bathroom which I don't use because I always find spiders in there. On the left side of my room is another room which is my sister's and left of the guest room is the office (I know this is boring but you need to know the house to understand the story).
After all of the rooms, there are the stairs which leads right to my grandparents bed room to the left, a bathroom to the right, and one of the two basements to the right just before the bathroom. Next to my grandparents bedroom is the living room and the kitchen is right next to that with the dining room through it. On the left of the dining room is the other basement which is where my parents room is, the laundry room, and 2 storage rooms. There are 2 doors in the dining room and one in the living room (which constantly stays locked).
Back to the story. Now I was in my room on the internet when I heard the doorbell ring. I went downstairs to the dining room and see who it is but no one is there. I locked the door again, checked the other 2 just to be sure and went back up to my room and started back with the internet. About 10 minutes later, I heard footsteps in the hallway right next to my room so I got up and looked to see if anyone was there. No one of course. So I went back to my room, thinking it's one of my cats. After about another 10 minutes, it starts again. Now I definitely knew these footsteps were like human footsteps, not cats. Once again I looked out my door and saw nothing. I looked to check the guest room and the door is open, feeling stupid, I checked to see if the cat had gotten in when I went in there earlier to get my sisters sleeping bag and thought I had probably left the door open. Nothing was in there though, so I closed the door and checked the bathroom. Nothing. I checked every room. Even the basements and nothing or nobody was there. All of my cats were in the basement near my room sleeping on the couch and that was all I saw.
I went back to my room and as I was going in my room, I noticed the guest room was open even though I had closed it. This kept happening to me all night while I was alone. I never saw anything or anyone. Something was there though, I could feel it in the air.
Every now and then, when I go to visit my grandparents (we moved from that house 2 years later but my grandparents stayed), I can hear footsteps and the guest room is always open.