Now, this sounds really weird, but here goes. Yesterday, my best friend and I were in her room, and it was just us two. She had her cellphone beside her (for sure) and I didn't touch it. She didn't leave the room once before we noticed it missing, I did, but I only went to the bathroom and we searched high and low there as well. We TORE APART her room, literally, searched EVERYWHERE. And later her mom and her did it again too, looking behind and underneath absolutely everything, no piecce of furniature was left unturned. And now this is REALLY pissing me off, because I'm fairly sure they think I took it, and I didn't. But if I were them, I would think it was me too, because really, there is no reasonable explanation for where the phone went. We tried calling it a lot, and eventually it was just turned off? Or maybe it died. Either way, I'm so freaked out because there's no explanation for it. Help?
Also later on we were SURE we heard the front door open, and footsteps. So we were scared and called down, but there was no answer and no more sound and we were too scared to check it out. So we called her dad and got him to come home and since then no noise was heard. But still... could a ghost have taken her phone? It literally disappeared into thin air!
I'm SOOOO freaked out.

This could be a ghost,tell your friend to ask for it back,she has to say it outloud of it might not work,after she has asked look again,this will only work if the ghost is nice, if it isn't I don't know what you have to do sorry

You don't think they are just joking around and it got a little out of hand?