¿Cuál es tu día de nacimiento
¿Cómo fue tu día? would be how did your day go to someone you know well. To ask someone you don't know well or should show respect to, say ¿Cómo fue su día?
¿Qué día es? = What day is it? ¿Qué día es hoy? = What day is it today? (Preferred Spanish sentence)
¿Cuándo es tu cumpleaños?
the next best thing
To celebrate the day of someone's birth.
Que dia tenemos hoy
Comó es tu día?
i will ask him or her if he or she wants to be a valentine for a day or for life.if yes then i will ask some time to decide it.
ask someone who cares
What day is it - ¿qué día es él? or, what day is today - ¿qué día es hoy?
When someone takes the time out of their day to wish you a happy birthday, you should look them right in the eye, smile and tell them "thank you." Should they keep the conversation going and ask what you're doing for your birthday or want to know how old you are, always ensure that you do not ignore anything they ask as they are genuinely interested in your day of birth.
It is customary that you ASK someone to be your Valentine. (Usually on or about Valentine's Day.)