It can last up to 2 weeks. The length of time that cold or flu germs can survive outside the body on an environmental surface, such as a doorknob, varies greatly. But the suspected range is from a few seconds to 48 hours - depending on the specific virus and the type of surface.
Flu viruses tend to live longer on surfaces than cold viruses do. Also, it's generally believed that cold and flu viruses live longer on nonporous surfaces - such as plastic, metal or wood - than they do on porous surfaces - such as fabrics, skin or paper.