Electrical items break, its completely normal in any house that over time things degrade and need replacing. If theres is something wrong in your home a phone call to the landlord is usually enough to get some one out to come and fix it. If for what ever reason your landlord is refusing to fix something then the best advice is to call you local authority. They can give you advice on what to do or even take legal action against a landlord.
I cannot stress enough unless you are qualified do not try and fix it yourself!