It is indeed difficult to help someone who refuses help. There are limited options such as involuntary commitment and a home intervention. Generally you can have someone involuntarily committed when you and another person ask the probate judge to sign a lay affidavit for involuntary treatment. The sheriff dept then can pick him up from home and bring him to a clinic where he may stay for up to 72 hours. Unfortunately, once at the clinic he can still refuse treatment/medication.
Another option is to have a family/friends intervention in the home for him and persuade him to seek help (does not have to be in a hospital if he is not posing imminent threat to self or another) If he is reluctant to take medication and go to counseling, find out what other options he may be willing to explore such as truehope.com, working with a hypnotherapist, exercise, etc.
Even though he has had some set backs, he has to realize that his state of mind and his situation is a temporary one. If he has some short term goals to focus on and work towards these, he may see that he's holding himself back when he's not getting the help he needs. If he flat out refuses to consider any help, then you do not have as many options to work with. It may be his disappointment that the medication had not been as effective and there are different medications available. He will have to be educated on the sorts of help available and feel like he has a choice.