Unlocking a password protected dmg - without the password

I created a disk image with a password to hold private files. The password was a long alpha numeric with symbols as well. I left a hint in the comments section of the file info. I didn't frequently access the image. Eventually, as my MacBook aged, the disk space began to fill. I uploaded most of the files that weren't regularly accessed to my dropbox account. I've recently purchased a new MacBook and downloaded the dmg. The file info comments appear to have been scrubbed during the process of sending to dropbox and then downloading it once again. Is there a way to recover the lost comment with the hint? Is there a way to access the content of the disk image without the password? Time machine doesn't seem to be an option. The last time the disk image (I update the file name with date when accessed) was 2016 if that matters... Thanks for any help - I think I may be screwed.