I have a promissary note from my brothers and they do not want to pay it. How long do I have before I have to take them to court? What is the statute of limitations?

The statute of limitations varies from state to state. Would suggest you take them to court before the time tolls on this.

2 questions need to be answered to give you an accurate answer.

1) What state are you in?
2) When was the last payment made to you?

... or if no payment was ever made how long ago did he sign this note... I'd just go down to small claims court and file the case and you will be told if it's been too long.