The reason that your array is not being modified is because you are using "==" instead of "=". So
if ((arr[levl][hr] == 2)&&(ok==0))
{
arr[levl][hr] == 0;
ok=1;
}
should be
if ((arr[levl][hr] == 2)&&(ok==0))
{
arr[levl][hr] = 0;
ok=1;
}
== Is a comparison operator and = assigns the value. Check your code very carefully and make it more readable for you could be able to find easy mistakes like that :).