I love to build stuff. I want to quit and start afresh. What career will be the best at the age of 30?
0) If you are having suicidal thoughts, you should get medical attention. Even if you're not "truly" suicidal, depression/anxiety will rob you of the power you need to do things. So first things first.
1) Unless you're into building skyscrapers or bridges or something like that[1], you don't need anyone's permission to build stuff. Do it on your own time. Learn things. Have fun. Use it in the short term to give your life shape and meaning.
2) In the medium term, look for or make opportunities to use what you learn building stuff to make money. E.g., if by stuff you meant software, this could look like a skunkworks productivity booster app at the customer service job or a web app you make for a friend.
3) If you do 1 and 2 long enough; stay flexible, adjusting course as necessary; and don't let fear/complacency keep you from taking some chances now and again, you will eventually find that at some point you became a pro at building stuff (or perhaps at some related, but satisfying niche).
[1] If you're into buildings or bridges or somesuch, obviously you'll also need degrees/credentials, but steps 0-3 will still work.
Good luck.
EDIT: formatting
I'd recommend getting into either Python or Javascript. If you can stick with it for a few weeks and not go crazy, it might be a good fit for you.
Good luck.
Your job might suck, but being unemployed sucks even more. Stay strong and good luck
Then you might try your chances in web development.
If your job is not too demanding, you could slowly build up your skills in an area you enjoy. In the meantime you could focus on your mental health without fear and anxiety.
Best of luck.
You can definitely change careers at 30. You might have started working at 18 or 22 -- I'll call it 20. From 20, you'll have at 50 years of work ahead of you. If you wanted to, I bet you could work effectively until 90 (if you like) with the pace that tech and medicine are evolving. If that's true, you're only 1/7th of the way through a professional life that can be as rewarding as you make it! http://bit.ly/2j5hivb Is there room in there for a change? The world (or the software industry) has no reason to include you, but it also has reason to exclude you. And it's lucky that you're not satisfied with your job NOW as opposed to four years ago -- the educational materials available for free online in 2017 have never been better.
I guess you can try to do something similar in your free time, the barrier of entry is very low and you don't have to spend money to learn and backtest and if you find an edge, it could be a really live changing experience... Having FU money should be the goal for everyone, because it gives you the ultimate freedom to live as you please and do whatever you really like...
"best" is a subjective word and you ultimately will be the judge of what is best for you. We can only give you some suggestions on how to find what you really want to do to grow your career.
Now, you first need to take a step back and identify WHY you are not satisfied with your current job. The Why matters. In your case, the clue is in "help me grow". So looks like you don't just want to do a job that does the same mundane customer service day in and day out. Ok, so you have figured that part out already. A lot of people don't even get there.
Make a list of your dream jobs. List at least 10 items. Write it down. Yes, it can be "dreamy" (read: unrealistic) but don't worry about that quite yet. Just make the list. I am sure you can come up with something. If you struggle to do even that, then think of people you may have met whose job you admire. Not just because of money but because of what they do. Make that list.
Go through this list every day and keep checking if some items on this list are still worth paying attention to. Perhaps, you can cross out 1 or 2 from that list after a few days because you KNOW that this was just a whim and not really something you would love to do. Keep refining that list.
As you do this, narrow the list down to 2-3 items max. Now, start thinking about the "realistic" part. The 'realistic" part should be determined based on what matters to you. Did you need something quick ? Perhaps becoming a doctor is then out of the picture. You know that to do that, you will need 4 years of undergrad, then med school and then another few years of professional education. At age of 30, if you start, you may take another 7-8 years which means you will be 38 when you can start practicing and not to mention that you may have a few hundred K of loan. Hmm, so if need something quicker, becoming a doctor is not realistic. Note that I am not saying it is impossible. It is just unrealistic for your needs.
Use this tactic and I hope it gives you some ideas.