Game glitch and loss of all gear while riding horse

While playing Minecraft in my friend's world while riding a horse, the game glitched.  During a jump, the horse would not land its 2 front feet.  Then it kicked me out of the game. I lost all of my gear accumulates over 5 months. Then, when I went back in, I was at World Spawn with nothing, even though I had my spawn point set. This appears to be a glitch in the game while on a horse. I was using the same username I have set up here, SittingMitten11.