how to access a local variable of one method into other method in same class in c#

The closest thing that somehow relates to your question that I can think of are ref-Parameters in method calls:

void SomeMethod()
{
    int x = 1;
    SomeOtherMethod(ref x);
    // at this point x==2
}

void SomeOtherMethod(ref int a)
{
    a = 2;
}

As you can see, ref-Parameters allow the called method to modify the value of a variable within the calling method's scope. But other methods that aren't called from SomeMethod() have no way to modify the value of x.

Heavy use of ref-Parameters is generally bad practice, you should think twice before using it.