How can a demoralized research student restore the passion for research?
If you lack motivation in your research because you feel like you lack the resources/knowledge to tackle the problem, then you should probably discuss this with your advisor. It is important that the advisor offers you projects that can be 'broken down' into small, manageable pieces, rather than some monolithic task. 

A PhD is often an isolating and depressing experience. You should find a support system of some sort to help you through the process. This can be family, friends, or fellow students. You can consider taking up a hobby (preferably something social, like sports) to give you an outlet that's not research. 

I can't comment on what exactly makes some people great thinkers, but I can say that in successful research takes a lot of hard work, vision, and a hearty willingness to fail 90% of the time.   

Finally, and I am sorry to say this, but you need to be mentally prepared for the fact that academia is not the right place for you. If it truly depresses you to the point where you don't feel like it's worth it, you should seriously reevaluate your prospects.