You can make a single menu() function instead of repeating the same thing twice.
You defined the function dep() but never really used it ??

Code:
case 2:printf("How much would you like to withdraw?");
scanf("%lf",&j);

amount = with(j);
j=0;
printf("This is your balance amount: %f",amount);
option 2 is for deposit and you are asking how much to withdraw!

and as others said--indent, use int main(), return 0, getchar() instead of getch() and get rid of <conio.h>