The database at some time in the past has had its design hidden. This involves two levels of protection -- a flag is set at the database level, and also individual design elements have their LotusScript source code stripped out and are flagged as hidden. When you try to edit such a design element, you get the message you've posted.
Somehow, the database-level protection has been deactivated, but the individual design elements are still flagged as hidden. I've seen tips posted on how to reset the database flag, and they seem to assume this will make the design editable again, but it does not, generally speaking. At one time there was a bug that could make the un-hidden versions of the design elements end up in a database that had the hidden flag set, but this bug has long since been fixed.
BY FAR the easiest way to fix this is to find the original template from which the design came, which contains the un-hidden versions of these design elements, and replace the design of your application from that.
If that template is not available, the task is considerably more complicated. I decline to give details on how to do it because design hiding is a security feature, and I don't want to publish hints on how to bypass that security. I will say that any LotusScript source code is gone for good -- it's not stored in the hidden design so there's no way to retrieve it. The object code is there and could in theory be decompiled, but of course you won't get back any comments, formatting, etc. Formulas can be recovered completely, and if you ask around you'll probably be able to find a consultant who can fix the design elements. If they're at all conscientious, however, they'll make sure you actually own the design before helping you.