Sorry, your screenshot has not attached. Can you link to an image somewhere?
Does it only happen with a particular file?
If you opened a .jpeg file and accidentally deleted the background Pixel layer (which would show as an empty Layers panel), then saved it (still as the same .jpeg file, using File Save or Ctrl/Cmmd+S) and closed it, that is similar to opening a Word file, deleting all the text, and saving and closing (I almost managed that once with the help of a cat walking on the keyboard).
I just tried it, you cannot recover the deleted Pixel layer after this process (especially once you have closed the .jpeg file).
Do you still have an unedited copy of the original jpeg file?
If you still have the edited file open, you might be able to recover the Pixel layer as MEB suggested, by using enough Undo (Ctrl+Z on Windows, Cmmd+Z on a Mac) or the History feature (an advanced undo manager, using a slider instead of constantly hammering Ctrl/Cmmd+Z and/or Ctrl/Cmmd+Y), possibly sliding right back to the start of the slider.
If you enable the saved history feature (File menu, Save History With Document) then saved as an .afdesign or .afphoto format (rather than just re-saving the file as .jpeg), you can still Undo even after closing and re-opening the .af(something) file.
It is possible to close or move (including off-screen) some of those panels - View menu, Studio, Reset Studio will put them all back in their standard positions.
