Hi Mark
I’ll investigate what’s happened, but in the meantime you should be able to recover by deleting the data folder for TiddlyDesktop. In Windows, I think it’ll be something like:
c:\users\yourname\AppData\Local\TiddlyDesktop
I think what went wrong with your drag and drop might be that by dragging to the blank bottom area of the TW window you won’t trigger the drop dialogue. Move around until you see the green bar before you release the mouse. (This bug isn’t TiddlyDesktop specific, and can happen in ordinary browsers too).
Best wishes
Jeremy