Do you know why the scores are so low? Was it because you had trouble getting motivated, or didn't understand the subjects, or had trouble learning things you were supposed to remember, froze up in the exam, or...?
Don't feel too bad about it - bad grades are disappointing for anyone, but if you were expecting high results then it's bound to feel even worse. You might want to look into re-taking the exams if possible, or even re-taking the entire subjects. If the school won't let you do this, find out if there's a college nearby that will.
I had to do my GCSEs at college, as I'd been home educated therefore didn't have a school to do them at. It was fun - the other students were there for very varied reasons; they'd missed (or done badly at) GCSEs at school because of health problems, missing too many classes, delinquent behaviour (those there for this reason were actually really interesting people - they just hadn't gotten on well with their school systems), and a few had done fairly well at school, but simply wanted a chance to get even higher grades.
The important thing to do is to work out why you didn't get the grades you wanted, and work with your teachers to do what's necessary to improve them. I doubt you're unintelligent, and even if you're not a genius - I've known some people who were far from clever, but managed good results from hard work and perseveration. If you want to improve on your results then you're capable of doing so.
Good luck, and keep us updated with how you get on.