Employers can set dress codes (which include hygene, make-up, piercings, body art, and fragrance) at work, and can do so both formally (e.g. by putting a formal dress code) or on an ad hoc or informal basis (e.g. telling employees when their appearance is not work appropriate). So your employer can tell  you that the way you have been looking at work is not acceptable and not let you work unless you change your appearance to meet their standards. This is a consequence of "employment at will," which is the law of this nation unless you have a written employment contract to the contrary: under employment at will, you have no right to or guaranty of a job, so you employer can set essentially any rules or conditions it likes for working.