In order to recover your lost on-chain balance you will need to use the 12 word mnemonic phrase which must be saved before the wallet is lost or destroyed.
Once an emergency happens you need to install the app once again on a new phone, then open a fresh installation and select the option to “Restore wallet” instead of creating a new one, then enter your mnemonic code. This is it, no further action is required.
Important note: restored wallet will appear empty at first as it needs some time to catch up with network.
If you don’t see a balance restored for a long time then first of all you should make sure your device has no connectivity issues. Normally a well-connected device displays syncing progress and shows a Wallet is operational message once syncing is complete.
When your device is well connected and synced but you still see a zero balance with no transaction history, this means that your restored mnemonic contains a typo somewhere.
In order to discover and eliminate a typo you can compare your saved mnemonic code with a list of all possible valid words. An in-page search may be used on to check if every word from your mnemonic is also present in the list. If one or more of your words are not present then simply fix any typos and try again.
Please take care to enter your mnemonic code very carefully when restoring your wallet. Any text is considered valid so even a single typo will be accepted, resulting in empty balance.