Hello Aniket,
Thanks for the response. I exported the .dat format and it loaded in ANSYS external model successfully. Earlier the problem was that i was trying to import a .inp file into ANSYS from Nastran!

Now I am able to see the mesh and also the loads in ANSYS, tough the simulation is giving an error 'Internal Solution Magnitude Limit Was Exceeded'. 
I read the solution to this error in ANSYS troubleshoot. But, the problem now is that i am neither able to edit any forces nor see there magnitude in ANSYS. Please let me know a possible solution for this problem.