Nothing works- this simply isn't true!
Okay, first of all, I realize everyone has their own journey, and the cause(s) of your personal struggle with tinnitus can be anything from physical hearing damage, medication or some other reason all together. Regardless of the cause that awful hissing/buzzing/tone is as annoying as all hell for everyone. And sure you think you tried everything, but there is so many possible things too try!
Once you and your healthcare provider has ruled out anything physical (which you absolutely should do first!), and you still feel stuck. Options that have helped many are:
CBT - this seemingly simple set of techniques has reduced distress for loads of people (including me). This is especially helpful if your tinnitus changes frequency which makes habituation hard. There are several good apps available, or a psychologist can guide you if you prefer.
Sound therapy - there is decorrelation therapy SMR, flanking noise, band-gap sound therapy , EAE therapy -all of which has actual scientific trials behind them. Chances are one of them will help you. Free and cheap apps available for this. Finding or knowing your frequency is a good place to start.
Masking - I'm not a big fan of this, but it helps when you really need a break. Gentle sound generators help. Make sure to use the right noise for you, Pink and Brown for Low Frequency tinnitus, and White and Violet for higher frequencies. Just don't push the volume up too high.
I'm not promising a cure for anyone, but you shouldn't lose hope that there's nothing to be done. A lot of active research in this field as well. What you shouldn't do is waste a lot of time trying to find out why you got it.
Hope this helps someone!