Explain loss of persistence.conf in known issues
Here is the template answer from our help desk:
Do you have the option to enable persistence at Greeter? https://tails.boum.org/doc/first_steps/startup_options/#index2h1 If so please do the following: Boot Tails, enable your persistence at Greeter and then go to Application -> Tails -> Configure persistent volume. If it doesn't ask you for a passphrase, then don't change any of your persistence settings, just click OK, reboot, and if you're lucky it will be back. It probably just is your persistence.conf file that disappeared. You can check on that by going (when your persistence is enabled) to /live/persistence/TailsData_unlocked and see if your files are still there.