A lot of people speak English in many parts of the world. ("in over" is not a common way to express this. "In many parts of" is clearer.)

Can you tell me where I put the big locker? (This sentence is grammatically correct.)

Would you mind telling me something about HCM City? ("Would you mind" is a more polite way to ask for information compared to "Could you please") - HCM stands for Ho Chi Minh City.

We haven't seen him for two years. ("We have" + past participle indicates a state resulting from a past action)

He said to me (that) he was going to come to my house next week. ("He said to me" introduces reported speech. You can optionally add "that" after "me" for clarity.)