Something that's disorderly is chaotic and messy, or unruly and out of control. A disorderly classroom might be the result of the teacher leaving for several minutes to answer a phone call.
It's one thing if your bedroom tends to be disorderly, with clothes and books scattered across the floor, but it's another thing to feel like your life itself is disorderly, confusing and unpredictable. Sometimes disorderly is used in a legal context to mean "destructive, or not law-abiding." You might be charged with disorderly conduct if you take part in a protest that's viewed by law enforcement as disorderly, or going against "law and and order."