Whew, boy. So many;
Madeleine McCann - No one took her. I believe her parents accidentally killed her and then covered it up by disposing of her body somewhere. Whether it was an accidental overdose of some sleep medication they gave her so she'd be asleep while they were out with friends, or if she had some kind of accident in the apartment such as a fall, I do believe they know what happened but the death was not intentional. There was too much risk for them to admit the truth - they'd likely face prison time and lose their jobs especially if they had been giving her medication (both were doctors I believe) and they could have also lost custody of their other children. They're not murderers but they are certainly guilty of neglect and covering up the incident.
JonBenet Ramsey - I actually don't think her parents or brother did it, but I do believe they covered it up. An interesting theory was brought up in a YouTube video I watched that analysed an interview with the Ramsey's. It was suggested that the parents discovered her body and thought the brother had done it, so Patsy proceeded to write the ransom note to cover up for her son. However when all the forensics/evidence showed it was likely someone else, they couldn't exactly go back on it as they were in too deep with the lie and had to keep it up. I had never considered this before but it makes a heck of a lot of sense.
Amy Bradley - She fell overboard, simple. One minute she was seen on the balcony then the next she's gone. She had been drinking, probably leaned over the railing to puke and subsequently fell. I also believe Rebecca Coriam met a similar fate.
The Dyatlov Pass - It was an avalanche; they fled the tent and one by one succumbed to hypothermia. Their bodies were then scavanged by animals.
Elisa Lam - She was off her medication. No paranormal or supernatural nonsense involved. The footage only appears "creepy" because it was slowed down to intentionally give this impression - anyone's movements would look creepy like this. She wasn't hiding from anyone in the elevator (or at least, not anyone who actually existed) and she was pressing the buttons to get the doors to close. She may have inadvertently pressed the door hold button as she seemed to be pressing a lot of them randomly and simultaneously. The tank was probably already left open so it was easy for her to climb in and wind up in there.
Kyron Horman - I don't believe the stepmother, Terri, did anything to him. Her timeline adds up and her movements after dropping him off and leaving aren't strange at all. If she had planned to kill him for whatever reason, why pick the one place they'd be easily spotted (there was a science fair at the time) and his absence would be quickly noticed when he didn't show up to his first class? I don't know what happened to him after Terri last saw him, it's really anyone's guess. I've seen some comments here mentioning the woods behind the school and how he likely got lost in them - this is highly probable however I do wonder why he'd have gone to them in the first place as he was last seen walking to class? The Dr. Phil episode was a shambles and an attempt to humiliate her. Who cares if she was sexting some guy and sending nudes? It was after the disappearance and has no bearing on the case at all.
Katelin Akens - I'm split on this one. The stepfather (I forget his name, sorry) is a little suspicious but at the same time there are other possibilities and his version of events make sense to me. For example lying about where he dropped her off; Katelin may very well have told him to lie about it because she didn't want her mother on her case about why she was at the mall. Her mother portrays Katelin as this incompetent little child that can't do anything for herself so it's not farfetched to think Katelin didn't want her knowing about it to avoid the hassle. The two friends she had been drinking with the day prior should have been looked into more, IMHO. The dumped luggage points to foul play and it was said the location and way it had been found suggested it had been thrown from the passenger seat of a moving vehicle, so potentially at least two people would have been in the car - how many friends was she with the day before? Two. Just throwing it out there.
Andrew Gosden - I think he ran away. Why? Likely due to bullying. A couple of weeks prior to his disappearance he began to walk to and from school instead of taking the bus. This suggests to me only one thing; he was avoiding someone/s on the bus route that was/were bothering him. He finally had enough and left for London. Where he went after that? I have no idea. I think the entire "he insisted on a one way ticket" thing is a red herring too, it doesn't mean anything if you know how UK trains work.
Russell Bohling - He committed suicide. Everything points to this yet his family insist foul play was involved.
I could go on, there are so many more. I really do feel for the families but for the majority of cases there is often a far more simpler, realistic outcome that they just refuse to believe. I guess it's easier for them to cope and claim foul play just to hold someone - anyone - accountable, rather than believe a loved one would leave on their own accord, end their own life or die accidentally.