It will depend on the type of contract you’ve signed. If you’ve signed an individual agreement then the landlord can’t expect you to pay any rent owed from another tenant or any damages they have done.
However if you have signed a joint contract then the landlord can choose to chase the person who owes the money, their guarantor if they have one, or they can decide to ask the rest of the household to pay. In this situation it’s possible you could be held responsible for money owed by a housemate. You can check if you have a joint contract here.
If you find yourself being chased for money it’s important not to ignore it, or it could end up with your and/or your guarantor being taken to court. Talk to the person who owes the money; you or they may be able to get some financial support from the University. If they’re a UK student they can check the Access to Learning Fund website, or they can contact LUU Advice if they’re an International Student.
It may be that someone has moved out and stopped paying the rent. If you have a joint contract then you are all responsible for finding a replacement tenant. Unipol’s student-to-student noticeboard is a good place to start.
If you need any help, call into LUU Advice.