Why would students contact a chancellor of the university? What difference does it make comparing to meeting a dean and associate dean?

Yours is not an issue that would be typically addressed by a university chancellor. A university chancellor is a business executive, rather than an academic official, equivalent to a company CEO. 
Typically, you would contact the department chair for readmission to a particular major.From there, you would go to the dean of your college (via an associate dean if that's the process), and from there to the university provost....Show more