"Doshite" means "Why?" (like "Why did you do that?"); "Anata wa" can mean "You", because "Anata" means "You" and the "wa" is the verb that is used for almost everything (like "Anata wa sugoi!", "You are incredible!"); "Sabishii" means "sad"; "Desu ka" also means "Why" but it is only used in the end of the question.
"Doshite anata wa sabishii desu ka?" means "Why are you sad?"
I hope that I helped you out! ^^
anata ga i nakute sabishii desu
Anata ga inakute, sabishii desu.
This can generally be translated as "[I] am lonely."
Politely: あなたが寂しいです "Anata ga sabishii desu" Casually: あなたが寂しい "Anata ga sabishii"
'Anata nashi dewa nakanaka mayotta ki ga suru'.
あなたがいなくて寂しいです anata ga i nakute sabishii desu
anata WA eg. you are stupid - anata WA bakka desu you are cute - anata WA kawaii desu you are a cat - anata WA neko desu
You may say 'anata/kimi ga suki desu,' or 'anata ga daisuki desu.' ("I love/really like you.")
simply, Desu. eg. who are you? - anata wa dare desu ka? where are you? - anata wa doko desu ka? are you ill? - anata wa byouki desu ka? are they new? - arera wa atarashii desu ka? ect. Desu means: Are, Is, and am.
わたしは、あなたがいなくて寂しいです Watashi wa, anata ga i nakute sabishii desu
anata ga inaito sabishii desu..." (I'm lonely without You...)
Best would be to say 'Anata/kimi ga koishii' (literally: you are so missed) (Anata would be slightly politer than kimi which is casual for 'you'.) There are several other ways to express it when you miss someone in Japanese. You can simply say 'anata ni aitai' (literally: want to see you), or 'anata wo natsukashindeiru' (I miss you), or 'anata ga inakute sabishii' (with you gone I'm lonely).