Hi Kailuamom,
It's wonderful that you're reaching out and trying to help your daughter through this - having that kind of support can mean a lot!
I've spent quite a few years struggling with anxiety, depression, and suicidal fantasies myself, and I've only recently started making real progress; I know everyone has their own struggles and their own way of dealing with things, but I definitely know what it's like to feel hopeless and alone, and hopefully some of the things I learned in my own life are helpful to you and your daughter.
In my case, one of the worst parts of depression and anxiety were the way they made it harder to move forward or get treatment, so I just ended up 'stuck' for a very long time. When I was feeling especially depressed or anxious, I just wanted to avoid the world and stay in bed, or drown myself in work or solo hobbies so I didn't have to be alone with my thoughts or risk being hurt by other people.
As others have suggested, the first thing I'd recommend is to find a therapist your daughter feels comfortable with - if she doesn't start feeling comfortable with one after 5-6 sessions, try another. Having the support of someone with experience in treating anxiety and depression is valuable, and a therapist can provide more ideas and referrals to others if needed.
I found that any kind of positive (or at least ok) experience out in the world, and that was different from my usual daily life, was helpful for me. It could be very simple things like going to a new restaurant, or a mall, or a park, or just driving through a different part of town - anything where I saw at least a bit of the outside world and that didn't go too badly was helpful, and I usually felt a little better after a few hours despite not wanting to do it initially. Since your daughter is interested in music, you could try a new music store, or going to some kind of performance or concert.
I found self care can be helpful too - especially diet, exercise, skin care, and a little fresh air and sunshine. It can be hard to do yourself while depressed, so any encouragement or low-pressure assistance you can give your daughter in those areas might be helpful.
Recognizing and celebrating the small victories was helpful for me as well. Anxiety and depression have a way of making even the simplest things, like cooking a meal or running a few errands, seem so much harder. I also struggled a lot with self esteem, so I just spent a lot of time feeling like a failure over the 'easy' things I wasn't accomplishing, but anxiety and depression are medical issues, not personal failings, and they really do make things harder. Acknowledging that, and recognizing even the seemingly small accomplishments can help build some confidence and make it easier to keep going.
I also haven't gone to any local LGBT+ support groups yet despite having a few around. In my case, I'm busy with everything else in my life as it is, but going to a local support group also has a way of making an already difficult part of my life (being trans) feel even more real and immediate, so I know that it's something I have to work up to and feel ready for before I can find the motivation to do it. Online support is easier to deal with for me as it's more anonymous, at my own pace, and doesn't require me to leave home and go somewhere unfamiliar. Maybe your daughter could find some support here on Susan's until she feels ready to meet others in person.
Making friends is something I've struggled with for a long time as well, and I've not made as much progress on that as some other things. I started out trying to focus on making friends before dealing with anything else (long before I was willing to admit to myself that I'm trans), but it's much, much harder to make good friends while you're struggling with depression, or being closeted and hiding a big part of yourself and worrying how others will react when they find out. Your daughter may find that making progress in other ways makes it easier to make friends, or if she's already much happier when focused on music, then trying to make friends in that setting may be easier as well.
Sorry if I've rambled on about all this, but hopefully others can benefit from some of the things I learned the hard way.
I hope that things get better for you and your daughter and that she's able to find happiness in her life.
-Megan