Why is using ingenting wrong here please?
Ingenting means nothing! Asking "do you need to buy nothing" doesnt make sense (:
It is right if we use någon instead of något?
No, någon can mean 'some'/'any' together with a word: Har du någon mat? 'Do you have any food?', but on its own means 'someone'.
This explains everything, thank you so much :D
why is "behöver du att köpa någonting" wrong?
behöva is a modal verb and doesn't take the att.
why not dig?
English uses "you" for both, but dig is to du as "me" is to "I".
So if this was in the first person singular, using dig would be like saying "Do me need to buy anything?"