Charge offs for loans, credit cards etc will leave a negative impact on your credit score for up to 7 years.
Charge offs are pretty bad for your credit and can lower your credit score significantly so do avoid getting things charged off and only open credit cards and loans that you're sure you can pay off.
Even though your account was charged off it doesn't mean you don't owe the money anymore.
You still owe the charged off amount and a debt collector will try to harass you into paying and your credit score can drop as much as 50 to 100 points just for one charge off.