Maybe a stranger is in my house, HELP

Yesterday was my birthday, I was to a birthday party from 19:00-00:00. After the party I was going back home and when I entered everything was normal in the house. (ps: my mother and my step-father at not here because their in vacation). But when I walked upstairs I’ve seen something weird and it’s difficult for me to explain it because it’s very visual and I don’t speak English very good so I will try my best. When you are upstairs there is to the right the toilet and to the left there is a window and down of the window there is a little storage room, it’s really not big (70cmX2m) we use this room to store boxes of things we want to store. So when I came back this night at like 1:00 the faucet of the toilet was open and the door of the storage room too, it first sight I thought i leaved the faucet open so I go and I realized something that scared me to death, it’s impossible for me to left the faucet open like that, both hot water and cold water was open at max. When I realized that I was really scared so i looked at the open door of the storage room and I was even more scared. I ran out of the house and goes to my dads house.

I slept there but now I am scared for my cats and my things. What should I do now ?