Isobuster won't work.
Every software I know seeks for the media information at first and does not respond to the operating system in this case.
The media information sectors are overwritten.
Perhaps there is a possibility to restore the information using the dd command.
The prerequisite is to know the address of the sectors in question.
After the address is known it is neccessary to find out how to access the sectors.
The sectors in question do not belong to the file system of the DVD.