repairing a water damaged screen

Hi,

A couple of months ago I bought one of those Acecase screen protectors that you need to use water to apply. I hadn't realised that since applying the last one my phone had had a very slight ding, making a tiny space between the screen and the outside casing that allowed water to get in.

The result was some aesthetical water damage to the screen, though it works absolutely fine. I'm just wondering if I were to replace something, what parts I would need to replace? I'm thinking of getting a whole front piece but I'm new to this so I don't want to get the wrong thing. The actual screen is fine, the damage looks like it's further behind it somewhere.

Any help would be appreciated!

Thanks