Man this is bad... you must have done some operations like interrupt/powerdown while it is writing to the wallet.

If you have a backup of the wallet.dat, use it and clean everything else in the config dir and resync from scratch, you should be OK.

If you don't, then it is possible you will lost the wallet, last try is to use something like pywallet (do a search in the forum) to see if you can retrieve things like private key from the wallet. But this never really work for me before.