The best thing would be not to have to recover the files in the first place. You can manually save your scene files at important stages or you can use the automatic tools in the Preference dialog (Customize Menu->Preferences->Files):
- make sure that backup on save is checked (that way if the file already exists it's moved to maxback.bak in the autoback folder),
- use auto backup to create a number of file versions which are saved every so many minutes (defined in the backup interval).
What to do when File->Open fails for a file?
In case you don't have a backup or previous file version you can try to recover as much as possible from the file.
The only way to open a .max file is with 3ds Max, apart from the Open command you can also try to use the Merge command (Import->Merge) as that lets you select which objects you want to import. To recover as much as possible from a file you can try to merge the objects in a new file.
If the file is too badly damaged no objects will be listed in the Merge dialog and then there isn't anything you can do with the file.
If objects are listed in the Merge dialog you can try to bring them in to a new file.
There are a couple of different approaches:
- bring them in one by one: basically merge in an object, save the file, repeat and if an object fails to merge skip it. Note that this would be very tedious if there are many objects in a scene...
- 'binary search', this assumes there are many objects in the file and that only one of them is damaged. You're trying to pin point which object is damaged by first importing the first half on the objects. That way you can see in one step if the problem object is in the first half or in the second half of the objects. Then you repeat with the half that failed until you find the object that's causing the problem.
Binary search example (based on the visible objects in the above screenshot)
- First you try to merge in the first half of the objects (highlighted in red):
Box001, Capsule001, ChamferBox001, ChamferCyl001, Cone001, Cylinder001, Gengon001, GeoSphere001, GeoSphere002, Hedra001. that works so the problem object must be in the second half
- So you try the first half of the second half (highlighted in dark blue):
Hose001, L-Ext001, L-Ext002, OilTank001, Plane001that works so the problem object must be in the second half of the second half
- So you try the first half of the second half of the second half (highlighted in green):
Prism001, Pyramid001, RingWave001that fails so it is indeed in the first half of the second half of the second half
- Ok, so now we know that one of these three objects is the problem.
- You try to merge in the first half of these three objects:
Prism001, Pyramid001that fails
- So you try to merge in the second half of the first half of these three objects:
- So the problem object is:
- Then you try to import all objects except Pyramid001 that works
The benefit is that you've used only six merge steps to get as much as possible imported from the file. If you'd done this one object at a time you'd have had 21 merge steps (20 objects and the final merge to bring the objects in). The more object the larger the benefit of using binary search.