To summarise the conclusion of that thread, you should begin by making a full backup. Then, once you are sure your backup is secure, you can delete everything except the
wallet.dat file in the
~/.bitcoin folder. This will cause BitCoin to re-download the block chain and restore the local block database. Don't panic if it initially shows a zero balance after restarting--it won't show your correct balance until it's downloaded the relevant blocks.
On a side note, this is also the safest way to perform an upgrade to a new version of the BitCoin software--backup everything, then delete everything except the
wallet.dat file. When you run the new version of bitcoin, your balance will appear once it finishes downloading the blockchain.
Don't forget to head over to the BitCoin StackExchange proposal to lend your support and vote on sample questions! It would be great to have a single place for BitCoin Q&A across multiple platforms and scenarios.