Hi Mohd,
you can add a reference to a dll or to an exe. So if the method (should be public) is part of an .NET executable, add that executable as a reference to your project. You can now add a suitable "using" declaration to your code and call it.
Modification
Code below assumes that in name space "my.name.sapce" there's class called Program that has two methods one of which is static and the other an instance method.
End Modification
using my.name.space;
...
public void Test()
{
Program.AStaticMethod();
Program p = new Program();
p.ANonStaticMethod();
}
...
Cheers
Manfred