Minecraft forge world gone?

I did update with normal minecraft then I went to cure forge and wanted to play with mods and my world is gone. What now? It's gone, I don't know why I just wanted to optimize the installation because it always lags so this micro lafs and optifien helps. But now my worlds are gone because I made an update on normal minecraft and then I'm on curse forge with worlds but nothing left? Why?

Overwritten and gone forever.

Yep

How so? How can this happen, what can I do against machete and with what pwritten?