Verilog: Counter is not working
Your count starts at  X (actually it starts 4'bxxxx.).

Now if you add 1'b1 to 4'bxxxx you still have 4'bxxxx. Sort of like a dead-lock

The only way to break this deadlock in your code is to apply a reset whilst the clock is running. That forces the counter to zero and after removing the reset you can use it to count.