If such a question arises and there is no data, neither what was the program encrypted, nor what was the protocol or standard encryption and "key bit", then I will answer simply - you, no way ... There simply will not be enough knowledge or special. software products ...
If this is a third-party application and it is simple, then uninstall it and that's it.
If it's built-in or professional, remember the password and decrypt the data. Otherwise, you will permanently lose this data.