As the person who asked the question, it's entirely up to you to decide which answer should be chosen as the "accepted" answer, or indeed if none of them should be chosen. You are also free to change your mind later.
What I would suggest you do is choose the answer which helped you solve the problem the most, even if it was only a partial or alternative solution. If none of the answers provided any help whatsoever, regardless of how well-written or well-intentioned, don't accept any.
The unfortunate part to this is that then your "acceptance rate" will suffer, since you will have received answers but accepted none of them. You have three options here:
Accept someone's answer even if it didn't help you very much.
Write and submit your own answer and accept that one.
Remember that you can - and are encouraged to - answer your own question, if you discover your own solution. This helps others with the same problem.
If you do this, it must actually be an answer. "Still having trouble with this" is not an answer. "I re-installed and I don't have the problem anymore" is fine though, as is "I've read up on it and the answer is it simply can't be done".
Leave it un-accepted and just put up with not having a 100% accept rate.
Essentially, it's all up to you how you choose to award or not award your accepted answer and these are only my suggestions. You can't really do anything wrong here since it's your personal choice - unless of course you're trying to spam or disrupt in any way.
Note that if you offer a bounty, there is no longer any requirement that the bounty winner becomes your accepted answer. You can choose a bounty winner, and choose a different answer as the accepted answer, or choose no answer as the accepted answer. It's mandatory to choose a bounty winner, even if none of the answers have helped (and if you don't, one will be automatically chosen for you). So I'd suggest that you award the bounty to the best answer you received so far, even if none actually help. And award the accepted answer to it only if it helped you (even a bit).