Aww man, I've heard stories of people discovering hard-drives in landfills with millions worth of bitcoin on it. That sucks. As for how to buy any of these coins. I should write an article on how to get started, but in short,

1. Create accounts at Coinbase and Poloniex
2. Buy something at coinbase (ETH/BTC/LTC),
3. When it arrives a week later (unless you use a credit card and pay more fees), transfer it to Poloniex and use it to trade for whatever coins you want.
4. When you want to back out to USD (real USD, not USDT) simply buy one of the three coins that Coinbase deals in and send it back to your Coinbase wallet.