It's a hard place to be in - feeling like you've 'failed' and have no purpose. For the first one, conventionally you may have failed (success here meaning getting a degree and going straight into a graduate role), but that doesn't have to mean that you've failed for life. It means that you're not where you want to be now, but it doesn't have to mean that you won't be where you want to be in 5, 10 years time. You still have plenty of time on your side
The second one - have no purpose - is a little harder. Whereas there is a 'conventional way' for getting a job, there are CV/interview workshops, online job postings etc, there isn't really much out there for having a purpose, because it's something that is very personal. Your journey through life, people you've met, things you've seen and experienced - these are things can affect and drive your purpose. Some people advocate that spending some time with people less fortunate (e.g. visiting an informal settlement in a poorer rural area) can provide some perspective; others say that it took a shock (e.g. losing a loved one) to unearth their purpose; others yet say that you don't need to do any of that, and that meditating on what you find important in your life (e.g. health, family) is the best way to find out what you can do to help others achieve that. There are many ways you can go about it, but I found that once you have an idea on what you find important, find a way that you can support those efforts.
For example, if you find that mental health is what you want to base your life purpose on, then you'd find ways to support mental health charities. Becoming an activist for mental health campaigns, volunteering some spare time to working with people with mental health issues, engaging with events on mental health, donating some of your salary to these causes. Some people find that the work itself gives them purpose; others are more goal-oriented and find pleasure when they hit measureable goals (e.g. every £X helps X number of people, campaigning for a law change that ends up succeeding). Find what works for you in that way as well.
Even after all this, a part of you may feel that you're a failure, that 23 years is too much time wasted. But all those people you help certainly won't. They won't be annoyed at you taking 23 years to decide on what to do - they'll be grateful that you spent the rest of your time helping people like them. 23 years feels like a lot of time gone, but don't let that ruin the next 60 years you still have to go!x
Much love <3