なるべく早くご返事いただければ幸いです。

I would appreciate a reply as soon as possible.

なるべく早(はや)くご返事(へんじ)いただければ幸(さいわ)いです。

Narubeku hayaku go henji itadakereba saiwai desu.

成るべく (なるべく)

as much as possible; wherever practicable

早い (はやい)

fast; quick; hasty; brisk; early (in the day, etc.); premature; (too) soon; not yet; (too) early; easy; simple; quick

御 (ご)

honorific/polite/humble prefix; honorific suffix

返事 (へんじ)

reply; answer; response

頂ける (いただける)

to be able to receive; to be able to take; to be able to accept; to be able to eat; to be able to drink; to be acceptable; to be satisfactory

幸い (さいわい)

happiness; blessedness; luck; fortune; felicity; luckily; fortunately

です (です)

be; is

Readings: ソウ、サッ、はや.い、はや、はや-、はや.まる、はや.める、さ-

Meanings: early, fast

Readings: ヘン、かえ.す、 -かえ.す、かえ.る、 -かえ.る

Meanings: return, answer, fade, repay

Readings: ジ、ズ、こと、つか.う、つか.える

Meanings: matter, thing, fact, business, reason, possibly

Readings: コウ、さいわ.い、さち、しあわ.せ

Meanings: happiness, blessing, fortune