“…i am replacing the power transitor with pmos but it becomes very hot and temp goes on increasing.”
“…i completely understand the working but because i want to use single tap which is cheaper and for that reason i wanted to modify the circuit using mosfet.”
Whether you use bipolar or mosfets for the pass elements of a power supply, with the same design and same load you will be dissipating the same amount of heat.
You aren't understanding what everyone is explaining to you. Until you're willing to read and understand what they are saying, you will continue to have these overheating problems. There is a big difference between linear and SMPS topologies and once you understand that and design your power supply accordingly, it will work much better. Perhaps you should read some of the references suggested above to understand the basics before you try to build a power supply beyond your current understanding.