I've burned a portable Ubuntu ISO onto a USB and booted it up on Macbook Pro 2017. I've selected the "try Ubuntu" option.
After using it for ~36 hours, I click "Suspend". Now, when I boot up the laptop again into Ubuntu and selected the "try Ubuntu" option, I see that it's a brand new copy—my 6 files on the desktop are no longer there.
What happened? How can I recover the lost data?