Don't forget your homework!
Don't forget to lock the door.
Don't forget that classes start at 2:00 this afternoon.
And please don't forget the des[s]ert! (Skills for Life (Entry 1); A1; Portuguese)
I've forgotten my keys.
I forgot my wallet yesterday. (Key English Test; A2; Portuguese)
I forgot to phone Jan.
Dad's always forgetting to take his pills.
I nearly forgot to tell you that the film is going to be on TV on the 15th of August. (Preliminary English Test; B1; Slovene)
I'm sorry, I've forgotten your name.
I completely forgot about Gemma's party.
I've forgotten what you do next.
I've forgotten how to operate this thing.
She'd forgotten that Lucy was coming over.
I'[d] forgotten that I had an English test. (Preliminary English Test; B1; Portuguese)
I'll never forget him for as long as I live.
But there are two things that I'll never forget: the taste of ostrich meat and egg, and the dolphins in the wonderful ocean. (Preliminary English Test; B1; Russian)
"I'm sorry I missed your birthday." "Forget it, it doesn't matter."
The teacher finally told me: "Forget it, it doesn't matter," and I felt so stupid that I couldn't do anything save going away. (First Certificate in English; B2; Spanish)
I forget when we last saw him.
The youth is the future, I forget who said that, but, its absolutely true. (International English Language Testing System; C2; Hindi)