Scratch does not have file IO capabilities, and i doubt it ever will.
The closest thing that i know of is importing/exporting a list. Right-click on the list watcher from the Scratch IDE, and export. It will produce a .txt file, with each list item on a new line. If you have a similarly formatting TXT file, you can import it using the same method. Each line corresponds to a list item. Comma delimited data doesn't work with this.