Lock all cells except one based on another cells value

[Muzzammil]

I have a excel sheet with a point system. if the user selects "Y" they can continue with the next question, but if the user selects "N" i want the document to lock except the cell next to the "N".

That cell is for a remarks.

So if they selected "N" they must enter a remark to continue with the questions.

And if no remark is entered i want it to stay on that cell were the remark must be entered.

Ive been searching on this for a while i cant find a solution.

Please help...