Formal:
* Bien sûr que je le/la manque. (Literally: "Of course I miss it.")
* Je le/la manque assurément. (Literally: "I miss it assuredly.")
* Je le/la regrette certainement. (Literally: "I regret it certainly.")
Informal:
* Bien sûr que je l'ai manqué/manquée. (Literally: "Of course I missed it.")
* Je l'ai manqué/manquée à coup sûr. (Literally: "I missed it for sure.")
* Je l'ai vraiment regretté/regrettée. (Literally: "I really regretted it.")
Note:
* le/la refers to the thing you are missing (e.g., "le café" for coffee, "la plage" for the beach)
* l' is used if the following word starts with a vowel sound.
Example:
* "I certainly miss the coffee."
* Bien sûr que je manque le café. (formal)
* Bien sûr que je l'ai manqué. (informal)
Remember to adjust the tense and gender of the verb "manquer" (to miss) to match the context of the sentence.