Hi, I'd like to help you with your question.
It sounds like your daughter is still seeing herself and reacting to the world as the child she used to be. After years of dealing with her self image being based on her looks, she has built up defenses to help her cope. Although she has changed who she is on the outside, she is still reacting like she did before. And the roommate issue is helping to reinforce these feelings for her.
You can help her in many ways. Acknowledge her feelings about who she used to be. Help her to understand that people will judge others based on how they look, but that she is worthy of love no matter how she looks. Let her know that you love her no matter what she looks like.
She also can try new social experiences. Tell her to go slowly, but to try something new. every once in a while. She is bound to meet some friends who see who she really is and pay more attention to her as a person.
Reinforce her good points when you talk with her. Tell her she is beautiful and smart. Let her know you love her and that you are proud of her. Tell her about good comments you hear about her and about others who love her and support her as well. When you are with her, talk to her about her view of things, from school to her opinion about politics. The point is to help her see herself as valuable and that her thoughts and opinions matter. It also helps her practice so she develops good social skills.
If she is willing, have her see a therapist. She would benefit from having a therapist guide her through rediscovering who she is and how to let her defenses down. She can also learn new coping mechanisms to deal with situations like her roommate and how to relate to boys. She can try on campus to see if they have counselors available. Or she can get a referral through her doctor. She can also try http://www.findatherapist.com/.
If she attends church, her pastor could help as well.
You can also help her by sharing some books with her about self esteem. Or you can read these yourself and use the information to help her. One book is called Self-Esteem: A Proven Program of Cognitive Techniques for Assessing, Improving, and Maintaining Your Self-Esteem by Matthew McKay and Patrick Fanning. Another is The Courage to Be Yourself: A Woman's Guide to Emotional Strength and Self-Esteem by Sue Patton Thoele. You can find these on Amazon.com or your local library may have them available.
I hope this has helped you,