All mobs dissapeared

I opened up my Minecraft world and saw all of my cats were gone but I ignored it because named creatures disappearing isnt really an uncommon occurrence for me, but then later I go to trade with my villagers and realized they were all gone (they were in an enclosed space) along with the minecarts they were all in. I look around my world more and realize all of my dogs, cows, and sheep were also gone. My horses had also disappeared along with their armor (both diamond) and their saddles. I also had dozens of armor stands; all with valuable armor on them that also went missing. I know this most likely can’t be reversed but I hope it can be fixed so it doesn’t happen again