You don't the wallet seed before you can recover the Ethereum wallet and through the Keystore file because the Keystore file also contains the wallet's private keys. If you know the first 5 alphabets or the number of your wallet privacy key you'll easily spot the wallet privacy key. I don't know how the MyEtherWallet operates now but it allows restore the wallet through the use of a Keystore file.
Check it if it still functions that way.
In order to access his wallet via Keystore file, he need to type his password too, that's make him can't access his wallet.
I think if @OP didn't remember few characters of his wallet, we can assume he already lose his wallet because brute force will take a lot time and it's not efficient. This is why everyone and developer always advice people to save the seed phrase, you don't have to worry if you know the seed phrase.