I bought it the day it was released.

  1. I bought it the day it was released.
  2. I bought it on the day it was released.
    Which one is correct grammatically?

They are both OK.

  1. I will seek from my doctor’s advice.
  2. I will seek my doctor’s advice.
    Are these sentences OK?
    Do they mean the same?

Only the second is correct.

“I will seek advice from my doctor” is also correct.

Alifathima, I think number 2 is good and as well clearer and a standard english.

1, should be ‘I will seek advice from my doctor.’
2. is okay.