Lost wallet problem: I have a 240 byte file from a 2013 wallet. Can I access bitcoin with this? I lost the device with my Android Bitcoin Wallet late 2013. At the time, I had stored a 'wallet backup' file. It has no extension, is 240 bytes, and begins with 'U'.
With only that file, is it possible to recover the value of the Bitcoin?
Please explain what the 240-byte string is, and what else would be necessary to recover the Bitcoin value.
That is very likely to be the &quot;Bitcoin Wallet for Android&quot; by &quot;Bitcoin Wallet Developers&quot; also sometimes known as the Schildbach wallet.
Other people on Reddit discuss having a file of that size created by this wallet.
Apparently the backup format changed from text-based Base-58 encoded private keys to a binary Protobuf wallet file.
It seems likely that the backup was encrypted and that you will therefore need to know the wallet password. I've no idea if encrypting the backup was optional in that software in 2013.
The process for either form is described here:

GitHub: Bitcoin Wallet - Recovering Bitcoins


This document describes how you can use a backup file on a standard PC to recover your Bitcoins. Normally, this shouldn't be needed. It is much preferred to just use Options &gt; Safety &gt; Restore wallet from within the Bitcoin Wallet app if you can.

i.e. first try installing the Bitcoin Wallet app and using its recovery menu.

Other discussion:

Bitcoin Wallet for Android - Issues decrypting the wallet backup BIN file using OpenSSL
How to restore from backup of Android Bitcoin Wallet
Reddit: Found Bitcoin wallet keys in my phone from 2013