How to-- Sothink SWF Decompiler
How to decompile SWF to FLA?

In the popup dialog, define the Export Path and Version. The program will list the recommended version by default.
Note: The file created by Adobe Flash can only be exported to FLA format.
Advanced Settings
Decompiler also provides some advanced settings which you can modify by clicking the button Advanced.

- Create folder in library for different symbol types: Checked by default. SWF Decompiler will save the exported symbols in separate folders according to their types.
- Convert static text to shape: This setting is to avoid the font missing on some computers during the decompiling process so that the exported FLA will keep the same text look.
- Generate guide line: Checked by default. Check or uncheck this option to choose whether to generate guideline when exporting the SWF with guideline to FLA format.
Tip: If there are some problem with the generated FLA, e.g. FLA cannot be opened in Flash, you may uncheck this option to see if the problem is avoided.
- Motion analyse precision: Set the precision level used to recover motion tween.
Check the link below to view video tutorial.
https://www.sothink.com/tutorials/how-to-convert-swf-to-fla.htm