If you connected to Facebook/Google/Apple ID within Fiona's Farm, you can connect to the same Facebook/Google/Apple ID account and keep playing from where you left off.

If you did not connect to Facebook/Google/Apple ID, your progress on the guest account (the ones you play without connecting to) is saved only on the device you play.

If you’ve recently switched devices, we recommend that you to connect to Facebook/Google/Apple ID on your old device first to sync your progress, and then on your new device to continue playing from where you left off.

Unfortunately, if you reformatted your device or deleted the game data while using a guest account, it is not possible to recover your account once the game data has been erased completely.