If by crash you mean hardware failure, then you'd need to make sure you have a backup of your wallet.dat file (latest version). Many people have 2 wallets. One is their 'savings' account that they keep in a secure location and the other is their 'daily/checking' wallet that they use for transactions. You would send BTC from one account to the other and back it up. You would need to keep your wallet file current otherwise you'd lose anything you've gained since the previous one.
Best bet: Get a Dropbox account and backup your wallet.dat (encrypted) to their server. You can use 7-zip to zip up the wallet.dat with a password and store it on Dropbox's server. Ideally, you'd have the Dropbox client on multiple computers so it will always sync to more than 1 location.
If you lose your wallet.dat file, then you lose the coins you have. There is no recovery.