Macro code where a cell freezes on the basis of values in other cell

Hi All,

I was working on a stuff where I got stuck with something. Below is the situation which I am trying to resolve. I already have a macro code I am just looking to incorporate the below condition in it.

if cell A2 = App then A5 would be unfreezed for the user to enter any value but if A2 is not "App" then A5 gets freezed with number "0" and user cannot edit it.

Any help would be highly appreciated.

Thanks,
Vik