How to recover erased and recorded over videotapes?

[Theofilos]

Please, it is important for me to recover erased and recorded over videotapes! Is it possible? Does anybody know how? I know it's difficult, but I hope not impossible!

[JVRaines]

Almost certainly not. If the erasure and re-recording were faulty, there is a very slim chance that some signal could be recovered, but it would take the resources of a government intelligence unit.

[johnmeyer]

No, it cannot be done.

This is completely different from "un-erasing" data on a hard drive. In that instance, no data has been erased, and only the directory entry has been removed. In that case, it is exactly like removing the card from the card catalog in a library: the book is still on the shelf, but the information on how to find it has been removed. Therefore, if you can take the time to look at every book in the library, you'll find it. In your case, trying to recover an erased VHS tape, the tape's magnetic particles have been rearranged. There might be traces of the original signal along the edges of the helical scan, but I doubt that even a forensics lab would be able to find enough signal to reconstruct anything.