The bookseller said to me, "Do you want to buy these books?"

The bookseller asked me if did I wanted to buy those books

The bookseller asked me if do I wanted to buy those books

The bookseller told me whether I wanted to buy these books

The bookseller asked me if I wanted to buy those books

All of these

Present Indefinite changes into Past Indefinite.

These changes into Those

Said changes into asked

Question changes into simple sentence