2003 trailblazer blower not working

Are you saying the blower motor would run intermittently and then just stopped working? My first thought is faulty blower motor, I've seen faulty blower motors that would run intermittently. Any motor that uses brushes, you can tap on the motor to see if it will start working, that is a sign of bad motor brushes, replace the blower motor. There could be other issues?
Did you check the blower fuse, not only check the fuse, check the fuse circuit for voltage, use a test light. Check for applicable hvac trouble codes. With hvac on, check for voltage and ground at blower motor wiring connector, if both are good and no blower action, suspect the blower motor.