The day before yesterday I installed the Minecraft Beta on my Android phone. Then I didn't feel like it anymore and closed the beta program and uninstalled and reinstalled Minecraft to get normal Minecraft back. But now my worlds are all gone. How can I get it back?
It probably also deleted the savegames when it was uninstalled.
They're gone forever now. You should have secured beforehand.
Did you have the location on "External" or "Application"?
If you had a backup of your phone, you're in luck and can download it
Unfortunately I don't know anymore
What exactly is a backup and how can I load it?
So a backup is a mostly encrypted copy of everything on your phone. If you made a backup before you installed the beta and since the worlds were still there, you can load it by plugging your mobile phone into the location of the backup, usually on a pc, and you can then also use the backup room in the Indian app select the backup and reload it.
