Formal:
* Je pense beaucoup à mon père. (I think about my father a lot.) - This is a polite and respectful way to say you miss someone.
* Je regrette beaucoup mon père. (I miss my father very much.) - This is a more direct and emotional way to say you miss someone.
Informal:
* Je m'ennuie de mon père. (I miss my father.) - This is the most common way to say you miss someone in an informal setting.
* Mon père me manque. (I miss my father.) - This is a more direct and personal way to say you miss someone.
Note: You can also replace "père" with "papa" if you want to use a more familiar term.
It's important to choose the phrase that best reflects your feelings and the context of the situation.