Okay I was in Riften, and then I entered Riften stables. I saw Serana interacting with the cooking place, but when I was outside she was gone. I checked the stables already. I've waited like a week and she still isn't there. I saw later that she was gone so I don't have any saves. When I try to get a new follower he/she says that I already have one. Please help me!!!! Serana was the only follower I liked and she has a lot of stuff of me

Found her like a minute ago just sitting in the winking skeever

Recently, in my new game, she disappeared in Castle Volkihar but after waiting for a few hours she came back. That never happened before.