If you don't then you can't know.
HOWEVER, my choice would be to try RECUVA in its deep scan mode.
Out of curiosity, why not backups? Today for smart phones, PCs and more, backup is no longer optional.
I accidentally deleted all my data while windows installation setup by running diskpart 'clean' command. Then I executed 'convert gpt' command and all my data was gone. I did not copy anything to my HDD after and is there any chance to recover my data again?
By googling I found by using TestDisk GNU software has some silver line to recover my data. But since I executed 'convert gpt' will it be possible?