Things can go bad with housemates and neighbours. Often the difficulty is around expressing what the issues are in a manner which is non-confrontational. You can discuss the options with your friend and help them to prepare and practise what they might want to say to resolve the problem. Together you might be able to work up a reasonable solution to the problem. If it is difficult studying at home, due to noise, lack of heating/air conditioning or other interference then finding alternative spaces to study in can be explored (local libraries, your institution might provide study areas and after hours study areas). Your friend may be able to raise the issue with a course co-ordinator and see if there are options for after hours study in tutorial rooms at their institution.
If the issue is with a neighbour and your friend has failed to get an adequate outcome then it might be time to look at more formal complaints to local government agencies. You might be able to assist in locating the appropriate agency to report to.
Landlords have been known to take advantage of people, and unfortunately international students (who may not be aware of what is appropriate and what is not appropriate behaviour for a landlord) are particularly vulnerable. If you learn that your friend’s landlord is not doing the right thing by their tenant then the best thing is to ring up and get free advice from an authority that deals with rental issues (e.g. for example in Australia there is the Rental Tribunal) which doesn’t mean that an official complaint has to be made. You may be able to do some research to identify such an organisation in your region.
Sometimes it might be that your friend doesn’t understand their commitments under a lease agreement and you can help them to understand what is expected, for example by going through the lease agreement with them.