My book was destroyed. Could you restore it, please?

Spyros Nikolaides shared this problem 1 week ago

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Some days ago, I copied my book. At the copied book, I made a lot of changes, delete many parts of my activities, leaving only the questions of each activity for teaching reasons. Unfortunately, I noticed that my initial book was changed at all, and much of the material, that I studied hours to prepare, was lost! Is there a way to restore (undo) my changed activities ?

Thanks,

Spyros N.