Is it possible to reinstate a patent which has been lapsed for failed maintenance fees for more than 10 years?
In Australia, extensions can be generous, provided there is evidence to back up why the deadline was missed. There will need to be a very good explanation for missing more than 10 years of maintenance fees!
It depends on the local patent laws. This is not an area regulated by the Paris Convention 1880 so local laws differ considerably from place to place.
Some countries have a defined cut-off beyond which it is simply not possible to restore and others have no cut-off but an increasing burden to show why the delay occurred.
A decision by the patentee to allow a patent to lapse and then a later change of heart is fatal to a restoration attempt.