A couple of ways to get an audio file back into a project…
If the audio file is already in the project pool for the project are working, you would right click the audio file and chose “Insert into Project”. It will insert into whatever audio track you have highlighted (new or existing) at the location you choose.
If you need the audio into a different project, then I would highlight the audio files I wanted and save to the desktop. Then open the other project and import (or even drag) whatever audio files you want directly into into that project and the pool.
BTW… you can delete your duplicate post before anyone replies to it.