How are various forms of energy ability to do work? According to various sources that i have come across, energy is the ability to do work. Can someone elaborate how diff forms of energy like potential energy and kinetic energy are ability to do work? I have tried searching but all i have found are the conservation of energy and diff forms of energy. Energy is such an important topic but all that is talked about are formulae of various potential energies and forms of energy and conservation of energy. 
 A: It may be useful for you to think of energy as work which has been stored up for future use. Here are some examples:
If we hoist a massive object upwards in a gravitational field to a certain height, we must perform work in the amount (work) = (mass)x(gravitational constant)x(height). That work is now stored in the system as potential energy. If a rope is tied to that object and also wrapped around a wheel, releasing the object will pull the rope and turn the wheel which could then set a machine into motion to perform work for us.
If we squeeze a coil spring's ends together through a distance l and hold it in that squeezed position, we have performed work on the spring in the amount (work) = (1/2)x(spring constant)x(l^2). that work is now stored up as elastic potential energy in the spring and if we stuck that spring between two blocks on the ground and released the spring, it would perform work on the blocks by pushing them apart.  
A: I think that trying get a full and accurate description of what energy actually "is", is a slippery subject. But your question might, I think, possibly be answered in this post: What is Energy?, 
Articles such as Wikipedia: Energy tend to be a collection, as you imply in your question, of lists of different ways in which we categorize energy by involving the source involved, nuclear, thermal, solar etc.
My own way of thinking about it is to view kinetic energy as the energy that actually does work, ultimately by electromagnetic attraction and repulsion in  most everyday situations and processes. 
I think of potential energy in two ways: as a (limited) source for the kinetic energy associated with it (which actually does the work), and also as a bookkeeping exercise used in our calculations to ensure that the law of conservation of energy is maintained.
A: Energy isn't the ability to do work. It's possible to have a system with a great deal of energy but it's difficult to get any work from it.
It's because of the conservation of energy that energy as a physical concept has become so important. 

Can someone elaborate how different kinds of energy like potential energy and kinetic energy can do work? 

If you put an orange on top of a table it has potential energy but it is not doing any work. A comet moving in empty space has kinetic energy but not is it doing any work. 
Work is defined as a force moving through a distance. Change needs to occur, in the sense of forces being applied, and distances moved through for work to happen. 
