If you died/If you were dead.
If I died/If I were dead.
意义基本上一样。
前者是要表达某个条件达成(你或者我死了)会发生什么事。Example: If you died, I'd be miserable. 这叫 Conditional mood.
后者是表达假设,所以用"were"。Example: If you were dead, I would grive for you every day. 这叫 Subjunctive Mood.
希望有回答到你的问题。
If you were to die
if you were dead
if i was dead