Kavod harav, Does one fulfill his obligation when davening in English if he says Lord or God for the names of Hashem? Or does he need to daven again?

Shalom, Thank you for your question. Even when praying in English it would be better to use the Hebrew words for G-d's name (Elokim and Hashem). One could learn the meaning and pronunciation of these name in a fairly short amount of time. The reason why it's better to use the Hebrew is because of the difficulty in translating accurately the subtle meanings behind each name. For example, we generally translate a blessing as “Blessed are You the Lord our G-d ..” However in truth it should probably be translated as “Blessed are You our G-d the L-rd ...” with Hashem being translated as “G-d” and Elohainu as “Lord”. None the less, if you did pray in English using the words “G-d” or “Lord” the prayer is acceptable. What is not acceptable is to use the word “Hashem” in place of the name of G-d, as is used in the Artscroll translation. If one said a blessing using the word “Hashem” instead of the real name of G-d, or the English translation, they would need to say the blessing again. I hope this is of some help -