This is why I said "make a backup of the wallet.dat"

-zapwallettxes just removes ALL the locally stored transactions in your wallet.dat file (if you have a backup, then you can always put it back if something doesn't go right). It should then "rescan" the blockchain and find all the confirmed transactions and your balance should be updated accordingly.
NOTE: if you are running in "pruned" mode... rescan will redownload all 150+ gigs.