Microsoft Excel : The value you enetered is not valid

Error Message when write something on cell :

"The value you enetered is not valid"
"A user has restricted values that can be entered into this cell"


Solution :
Click on the cell, then on Menu bar Go to Data > Validation and check each of the tabs to see what is there. Then check or uncheck as appropriate. Probably the first tab, that has some kind of list.