Encryption Key Stopped working

My Encryption key stopped working without us making any changes to the key. We had to change it keep getting the submissions. Is there any way to get the 4 submissions that came in encrypted? We are a mortgage company and these submissions are extremely important. 

Unfortunately, a new key won't decrypt previous submissions. If you still have the original key, try logging into a different browser to see if it decrypts those four submissions. If it does not work, I am afraid that there is no much we can do, since the encryption keys never make it to our servers.

Do you know why it suddenly stopped working? I'd like to figure that out so
it won't happen again
...

Please note that if you disable encryption in form and enable again, it will download a new key file which will decrypt only future submissions you receive after enabling encryption again.

If you were able to decrypt & view submissions and suddenly it stopped working, than only possibility I can think of is that you must have cleared browser cache including browser storage. This clears the uploaded key file and you need to provide the key file again to decrypt submissions.