"I read books in my room."
Translation:Odamda kitap okurum.
It's not wrong, but it's only used in literary contexts. If you were to speak like that all the time, you would look awkward. That's why we won't accept it on Duolingo.
I got 'Ben kendi odamda kitap okurum.' as the correct answer though I have no idea what 'kendi' means...
It must be Ben odamda kitap okurum. The sentence order was wrong. The subject must stand in the beginning of the sentence