First a tetrazolium test, nex the type of protection on the seed embryo (dormancy or not).Later the usual methods to understand how this family of plant is classified based on the presence of dormancy. A survey in the literature can also help you. I suggest: Plant Cell Physiology; New Phytologist, Plant Cell, Plant Molecular Biology.
Inability to germinate may be because of many possible reasons, the following two are just examples:
(1) The seeds has lost (very low of) their viability and vigor. With time (i.e. during storage), seed will gradually loose their ability to germinate. In this case, the seeds lost their ability to germinate. A number of seed treatments can be used to obtain some level of germination from such seeds, such as: seed priming or seed-conditioning, with or without addition of KNO3, plant growth regulator, and so on.
If you have previously stored your samples for a long period of time, it may have gone bad (viability and vigor may have lost during storage). Seed treatment may be able to recover some germination from the seeds.
(2) The seeds may have been dormant (i.e. it has not ready to germinate yet). If this is the case, then you may need treatment to break the seed dormancy. The appropriate treatment will depend on the type of dormancy presence in the seeds. There may be physical constrains, biochemical, or physiological ones resulting in the seed dormancy.
If the seeds are dormant, unless you break the dormancy then you may not be able to germinate the seeds. Find out which type of dormancy exist in the studied seeds and apply the appropriate dormancy breaking treatment to the seeds.
Thanks guys for the impressive answers. If i may ask is any one of you working with this particular plant? I will like to request for some seeds from any of you in order to try out the methods you provided.