I just want to remake the mydata.tgz from extracted home and opt directories.
Lets pretend your current system is working but some files are missing but are in your mydata.tgz backup? As I am not sure what you mean otherwise. So I am assuming you have 2 mydata.tgz
one....at correct dir and another somewhere else that contains the missing files
Literally try this...
open control panel -> click the Backup/Restore button
click on included for backup
Check what is missing.
If you have a persistent home....that is your responsibility to ensure files exist over reboot.
I am sure you understand that by now. If you have a true fully persistent home, I am not sure how you can missing files from it.
but lets pretend you need a file with pathway
/usr/local/lib/libabc.so
and its not showing in above list
so you must use root powers to extract it from your "backup" that contains it
and add that file to /usr/local/lib
Next add that file in the backup GUI
Next pulldown "Dry Run" and choose Backup.
click go
-> that new file must appear in the list.
Please note you can only have one backup file at the root of your tce dir
called mydata.tgz
there are other options.
Personally I like using a terminal file manager that can unpack that file
its called mc.
here is a screenshot if interested.
https://imgur.com/AXWyP0K