How to Create New Genesis Block?
genesis.GetHash("");


This is incorrect. GetHash does not take a parameter, as said in the compiler error. This should just be genesis.GetHash();.


  I have checked the debug.log but i dont see new values for hashGenesis and Merkel root.


The debug.log file is only modified when  you run the program, and because it isn't even compiling, when you run it, you are not running it with any of your changes.