Hello,
Last year I got my AS results and I was devastated: BCDU. I then moved to a different college, with a different set of subjects that were respected and that I enjoyed, and today have come out with AAAB, and am now looking at a strong UCAS application to a Redbrick/ Russell Group university, and I can honestly say I couldn't be happier.
I don't know exactly why you got the results you did, however (despite what people say) it is a really big jump from GCSE to A Level. My advice to you is to apply to another sixth form, and re-do the year, with subjects you will do well at (but are not regarded as 'soft'). Your whole approach needs to be different: you need to study consistently throughout the year, and when you revise, do not waste time writing colourful notes and fooling yourself into thinking you're doing 'hours' of studious revision. Instead, your one and only aim with revision is to make sure the information goes in.
It really won't feel particularly strange re-starting sixth form: you're a year older than everybody... and quite honestly it's kinda like going back in time... Honestly though, it makes no difference whether you're sixteen or seventeen.
Whilst the majority of courses will still be open to you, I am afraid to say you will struggle to get onto the HIGHLY competitive courses even with 4A:
Medicine
Engineering
Law
Etc, etc,...
But if you do a solid degree at a top uni, and get good, relevant work experience with a career in mind so you can develop some practical skills, then all hope is not lost.
I wish you the best of luck.