On 17th of march you get the task of finding the 3 missing accessories i went to all of the places and looked around where the gir told me to but could still not find any interactable characters how do i get the accessories back

One of the accessory can be found by talking to Anny (when you get out of the classroom, you go left and you should find her there on some day).

The second one can be found by talking to Jessica (She's on the second floor of the dorm, playing blackjack with Melody at night ,on Thursday and Friday)

The last one can be obtained by talking to the teacher Ms.Johanna (She's in the teacher's room on some day, it's the first open door when you go left from the classroom)

some characters appears only on certain date.

Note that if you wait too long to finish the quests, there's a chance you'll be stuck and need to restart the entire game.

I really hope that'll help you, if you did all that in time but still couldn't obtained the accessories, then I'm afraid it's a bug of some sort.