You’ll find instructions at http://www.axantum.com/AxCrypt/LegacyRegistry.html to find a registry settings to enable it to try even with a broken file [as per svante explained in the last response].
You can also try to decrypt the damaged file with the AxCrypt 2.x app.
AxCrypt 2.x has a feature called Try Broken File. You can decrypt the corrupted/damaged AxCrypt encrypted files by navigating the menu Debug | Try Broken File from the AxCrypt app.
First we need to enable the Debug menu via the menu options File | Options | enable Debug from the AxCrypt app.
Navigate to the debug menu and click the Try Broken File menu option.
Now we will be prompted for file selection.
Select the corrupted/damaged encrypted file and then AxCrypt will try to decrypt the file. If successfully decrypted then you are able to see the decrypted file in the location. Otherwise AxCrypt unable to process(decrypt) the file.