“Hey, long time no see. I hope you’re all doing well.” - sounds more native/natural. 🌈 🤗 Nicky In your original sentence you’re missing a period between “well” and “long”. (Hello, hope you are all doing well. Long time no see.)

There’s no any mistake in the last sentence)

He didn't know that it was I who did it. On the other hand, "It was me" is a grammatical error made by many native English speakers.

Agreed. It's perfect.

No errors. That looks good to me 👍🏼