How Ro Restore Deleted Firefox Nightly Profile Folder

When having restarted my computer and Firefox Nightly after a sudden power outage, all my tabs were gone. I need to restore them. I went into the profile folder, but there was no session store file. Inside the backup sub folder i saw two large files, "previous.jsonlz4" and "restore.jsonlz4", and made a copy of both and placed them inside a new sub folder that I made, inside that profile folder. An expert from the "Tech Support Guy" website ("Nader") told me, to open "about:support" and there to use the "Refresh" feature. I did this, but no tabs were restored. So I went into the profile folder again, just to see that it had disappeared and been replaced by a new profile folder! And therefore my two copies of the PREVIOS and RESTORE json files were gone, too, as they were inside a sub folder within that disappeared profile folder! Now I need to know, URGENTLY, how to restore that folder and the files and sub folders within that profile folder. Thanks!