is there a limit to how many files you can have in a save file? also, is there a way to create a new one? i only have one and also it seems as if some saved generations have disappeared. 

If you click on the filename or the little eject arrow, it opens up a dropdown view of all of your savefiles that you can then choose from. I'm going to have it open by default in the next update.

ok maybe i didn't say it right. Is there a limit to how many files you can have in the folder and is there a way to make new ones?

There is no limit on the number of save files. You can create new save files using the "Save" button or the autosave toggle during simulation. You can't create new save folders.

oh ok. if there's no limit how come it looks like some files have gone missing?