If you are struggling with drug or alcohol addiction then you need detox rehab. The whole point of this is to give you a clean break so that you can get your body dried out from the drugs and the alcohol so that you can get started on living a new life.
This all depends on where you are at in terms of denial. Some people actually still believe that they can change their life while they are still using drugs and alcohol. If you come to a point of surrender then you may realize and stop fighting against the fact that you cannot successfully use drugs and alcohol. You will make peace with the idea that you need to stop using everything in order to change your life in any sort of meaningful way. You may have been trying to desperately control your drug or alcohol intake in an effort to change your life, but you will have seen how this approach never really works in the long run. We can fool ourselves for years and years because when we try to make small changes (like switching from liquor to beer, or from doing drugs every day to just using on the weekends), we make a tiny bit of progress for a short time and we seem to be a little better due to our new strategy. But of course if we are truly addicts then we always end up going back to our old ways and using drugs in full force again.
Breaking through this denial means that we finally see and accept the truth: that we cannot use drugs in any way and be successful with it. We see that we will always lose control eventually and screw up our lives if we continue to self medicate with drugs. This is the point of revelation that we need to get at in order to make a major change. Now once we are there, we need to get ourselves into rehab or detox as fast as possible. Doing so will give us the best chance at starting a new life for ourselves and making long term progress.
Getting to rehab is the key, and after we go through detox, we will likely be exposed to residential treatment and hopefully a whole treatment program. The idea is to find a new way to live our life and stay clean and sober. This process takes time and there are bound to be some bumps along the way. But if you have made the decision to do something about your drug problem, then it makes sense to go to rehab and get started on this process.