Why did my cold just dissapear after two days of catching it?

I started to have a cold on sunday night up until yesterday. I had all the common symptoms: chills, stuffy nose, congested, muscle aches nd so on, but now all of sudden its gone, the weird thing is i didn't take any medicine.All i have now is a dry cough nd some sniffles.Do you think my cold will come back? What does this mean about my immune system? Good or bad thing?