modified LCM func.

[chaitanya57]

works fine.!

[oyeb]

Try 3$4. Or 6$7
[Errors]

[oyeb]

You are tracking a temporary file ml_lcm.c~, never do that!
But that's not the issue, Your function "hangs" for the inputs I quoted. So I inspected the function, it's pretty clearly wrong.

for(i=a;;i++)
    {
        if(a%n1==0 && a%n2==0)
            return a;
    }

The loop variable is i but in the if, you test with a.
I suggest you use the well known LCM(a, b) = a*b/GCD(a, b). I believe that is an optimal solution.