Community nuisances are always Frustrating. But when you share walls with the a neighbor that is engaging in nuisance behavior, the problem is especially vexing. The good news for renters is that, in addition to all your other options, you have built-in allies in the battle to keep your apartment livable: your lease or rental agreement and your landlord. Remember the lease or rental agreement you signed? Chances are your neighbor signed one too. Standard leases and rental agreements contain clauses that entitle you to "quiet enjoyment" of your home. A neighbor who is blasting the stereo in an unreasonable manner is probably violating the lease or rental agreement and can be evicted for doing so.
If you warn your neighbor about the noise in writing and are sure that your lease entitles you to a reasonable amount of quiet, send a copy of the lease along with your letter. In your letter, tell the neighbor that the next complaint will be to the landlord or neighborhood association if the noise continues.
If warning your neighbor doesn't work, go to your landlord. Most tenants don't like to complain to the landlord or manager about unreasonable noise or other nuisances because they are afraid of being branded as troublemakers. But other neighbors are probably bothered by the nuisance, too. Get together with them and complain to the landlord as a group. It's easier and you might get faster results. Most landlords don't want arguments between tenants and won't put up with tenants who cause trouble by ignoring signed lease or rental agreements. Your landlord may tell the noisy tenant to pipe down or face eviction. If you landlord refuses to help you may want to consider taking him or her to small claims court so as to address the landlord's responsibility to provide you with 'quiet enjoyment'.