My friend's F-1 visa has expired but she stayed in the States til now. She wants to know if she can get into grad school now even without a visa?

Whether your friend can get into graduate school will depend upon whether a school is willing to accept her. However, if she failed to maintain status, she will not simply be able to obtain F-1 status again in the United States. She would need to depart the country and apply for a new visa. The chances of the visa actually being granted are slim.