People that time didn't expect bitcoin to be with huge value. To them it was just a play virtual money even after the price went up and now that they have seen it become serious and its even advertised on ball games, they are reminded of the wallet they did back then. Too late though because if they lost the priv key and they forget the password then its lost forever.
If you lost your privatekey, there is no way to recover it,if you have your wallet.dat and lost your password, maybe if you put a weak password, you can bruteforce it.BTCBTCBTCBTC