Tileset on right missing

my current tiled.io look like this
but i lost this part

how do i make it back?

You can bring back the Tilesets view using either:

  • View > Views and Toolbars > Tilesets (checkbox also available as context menu on view titles bars and tool bars)
  • View > Views and Toolbars > Reset to Default Layout (for resetting any view customizations)