Worlds Deleted

I haven't been on my Minecraft world in a while, It was a city world that I have poured over 5 years into and I don't want to lose it, I went to log in today and all of my worlds are gone. I did have a random power outage recently, and I have not messed with any of the files or recycled any of them to my knowledge. I don't know what to do and I am worried that I will lose all those years of work.