I'm 26, never had a girlfriend or job, no qualifications. My dreams are modest but I doubt I will ever reach them. I live a solitary, miserable life.
I'm sorry to hear you're feeling so down.
What dreams are you hoping to achieve?
Financial and practical independence, a nice girl and a career in horticulture. Plus a good social life and just happiness.
I know it's tough, but you still have time to achieve those things. In terms of your horticulture career, perhaps you could work part-time to start with (maybe somewhere like a garden centre), then you could build up to doing more work/a different route when you're feeling able to? I spotted on your other comment that you've been struggling lately, so maybe just a few hours/couple of days a week would be a good way to get started.
There are social groups you can join, which might help you to build a social life and meet people. I know of a group called Spice that arranges all kinds of outings (everything from evening classes, to day trips, to walks, to holidays), and once you're a member, you just sign-up to whatever activities interest you. It might be worth a look.