Re: friends roomated screwed her over..
Like everyone's saying, unless you have an agreement between the two of you regarding payments, she's up a creek. The landlord or apartmant management company does not care WHO gives them the money. They only care that SOMEONE gives them the money. Usually if rent isn't payed, the penalty is an eviction and negative credit scoring. I'm sure she doesn't want negative credit scoring.
Maybe yer friend should tell her friend that if the rent isn't payed, since they both signed the lease, BOTH of their credit scores will be adversely effected. Maybe that'll get her going, maybe not. She could always appeal to her as a friend and be like "hey, yer screwin me over, ya bitch".
If they can't work it out, she should consult an attorney, as murph suggests, but most attorneys, unless they're total scumbags, will tell you if there's anything they can do before they take yer money (i.e. free consultation)
2004 Mazda3 i sedan || Automatic || Strato Blue