CnW Recovery is a software only program and so there are limitations on the types of recovery it can do. It does rely on being able to see the drive as a physical device within Windows, typically as a USB or IDE device.
Good signs
Drive spins
Heads move
No clicking
No very hot spots
Bad signs
Drive not spinning
Drive clicking
Hot spots on controller board - or smoke
Any of the above normally means that a physical repair will be required. It could be new heads, controller board / firmware updates or a new motor. It is not possible to repair every drive, inparticular those who have suffer platter damage.
DO NOT open a drive unless you are qualified repairer - you will do far more damage than good.
If a drive has a failure of the controller board, or will not spin then no software only solution will work. If the drive is recognised as a physical drive, then there is a very high chance that CnW Recovery will beable to recover data.
For CDs and DVDs it is always recommended that a full RW drive is used to recover data. These types of drives have features that will enable disks that have not been closed to be read. However, not every unfinalised DVD can be read - some will require services from CnW office who have a modified drive to read such disks
If there is any question of whether the program will work, the quick answer is to download the demo and try.