So it seems you have more than enough experience to think about the certification. Good that you shared your unsuccessful story, we have seen some similar here recently, meaning that you're not alone and in fact I think only very few people post failure cases, numbers probably are way higher than we think. After all, even though certification is meant to cover only basic Java techniques, exam isn't easy at all, so don't lower your self confidence.
Yeah, certification won't give you an actual experience, but hopefully will give some self confidence during the interview, so, you will pass this test
- earlier or later! I see you took OCAJP7 version. Current newest is OCAJP8, so maybe would be a good idea for you to get the book for this version and go through the book once again? In this manner you'd repeat common material between both versions (7 & 8) and would learn some updated topics and on top of that you wouldn't be bored to go through the book again.
Interviews - this is something what requires some other skills. Knowledge might help a lot, might not. In my opinion it is important to show potential employer your enthusiasm about what you're doing - maybe talk during interviews about your project you did in a college? Or along with certification, do some personal project (android app or some desktop or web app), not necessarily it has to be big, importance is, that you'd have something to talk about with potential employer instead of dry ping pong - do you know that? [yes/no] how you'd do... what is the... Get an idea? Employers I think want to see that programming is part of your hobby, part of your free time (spending time on forums, contributing, reading / answering various topics / being in that on daily basis) - it is important. Why I'm saying that, when employers say you don't have work experience, well, you can't get it without working, right? So, something isn't quite right about this statement. More probably of a - they didn't manage to see some other aspects. Hardly you go to company and start working from day 1, you get training (lots of them), you research yourself, and bit by bit you get used to it. You need to show your motivation during the interview. In order to get invitation to an interview - you need to have a resume which attracts. So, my advice along with that is to put more information about some actual cases you work or worked on. Don't waste page space writing - I'm a team player, I can learn fast, I know A, B, C, D, E, F, G... Better write - I know A and during my recent small project I was working on, managed to combine this with B, which in fact gave me a better understanding about underlying principles... Some kind of stuff, isn't it? But as a story, rather than a dry A, B, C... Why is it important? Because during the interview, the employer more likely will be attracted to question you about that stuff, and you'll have a chance to talk about the thinks you know rather than answer to their "tricky" questions you might won't feel confident about. Once interviewers see you know a little about your stuff, the rest of the job they will do - will give training on the things you need.
It seems I went off the topic. Sorry. Just wanted to motivate you a bit. And last thing - don't expect to be accepted from each company you're going to be interviewed, many things need to match between you and potential employer, so there is nothing weird that you "lost" (as you say) many opportunities - there are more opportunities out there, so no worries
Now, get some self confidence, go through the book once again, do some mock tests by analysing where and why you mark answer incorrectly and things should get better - you already improved your highest score from 40% to 63%, so it seems you just needed a bit more towards that. And hey, you got 60% in the exam, where passing score I think is 63 or 64%, which is one or two extra correctly answered questions - so you're quite close. Just don't rush yourself this time by desperately trying after a week or so go to sit an exam again. Train yourself a bit more.
Don't forget to come back and post your success story when you pass. More better, be around reading these forums, so you won't need to come back