version is newest 0.5.12, 0 . I'v send to my multibit some BTC, then I waited for a very long time and it still shows unconfirmed, on blockchain.info shows transaction was finished, so I pressed the button "reset blockchain and transaction", then balance became zero, I waited 6 houres and it's still zero, how long will the sync take?! in the message said"Synchronised with network." , means sync finished? but balance is still zero?!
It sounds like you are trying the right approach. There is a support note here: https://multibit.org/en/help/v0.5/help_support_sentBitcoinToMultibitButTheyNeverArrived.html
You can try it again safely. Check all the details like the address is what you expect etc.
edit: And if that fails, you might want to try:
1) Exporting the private key (unencrypted)
2) Importing it into a blockchain.info wallet you create. You should then gain access your bitcoin.
If you do have to resort to exporting the private key please post that that is what you have done. (I am the lead dev for MultiBit so would want to follow up on it with you).