After some time away, I respawned in my worlds at spawn and lost all items and levels

I've been playing in realms for a few months, and haven't played much in my worlds, of wich I have five. I last entered them a couple of weeks ago. Tonight, when I tried playing in them, in each and every world I restarted at the world spawn with no items and no levels. My builds are okay, or they seem to be from a cursory inspection, but I've lost everything in my inventory, and everything I had been holding and wearing and all my xp from the last time I played.