Most Excel functions blockeds

I didn't know if I made a fat finger here, but I was working on my spreadsheet and tried to add a note to a cell, and then I noticed that almost all of the excel functions were blocked (the note as well).

I use Office 365 family pack. 

I've already tried to turn off the "protect view" options but the problem has not been solved.

Edit: the problem is with this worksheet because I created another one to test and it is working well.