If you aren't able to edit the permissions, you may have lost access to these objects.
Bucket and object permissions are completely independent; an object does not inherit the permissions from its bucket. For example, if you create a bucket and grant write access to another user, you will not be able to access that user’s objects unless the user explicitly grants you access. This also applies if you grant anonymous write access to a bucket.
Your ownership of a bucket still allows you to delete objects you don't otherwise have any access to, but there doesn't appear to be a mechanism to allow you to assume ownership of an object.
The only other suggestion might be to open a support request with AWS, but it seems unlikely that there is a mechanism that would allow S3's built-in security design to be overridden.