I can't find any of my Minecraft worlds on my Bedrock account

I just went on to the app one day, and found that all my worlds (that I had spent an uncountable amount of time on) were gone, and didn't appear onscreen. This is either a bug, a glitch, or I've been hacked somehow. I have no idea how this came about and I would greatly appreciate your help, as I am a gaming YouTuber and can't post without my content.