The short answer is no, they're not going to refund your unused days.
Given when I think your package was purchased you likely have the 5-for-3 tickets, which means you paid the price of the 3 day tickets and received 2 days free. If that's the case then since you have 2 free days there's absolutely no way they're going to give you any refund.
If they were to allow a refund, they'd likely do it based on the current ticket cost. They don't have a 4 day ticket so the best you could hope for is the cost of a 3 day and a single day (parkhoppers all). The 3-day is $129, the single day hopper is $69 for a total of $199 USD. I'm guessing that you paid less than that for your tickets, so therefore there wouldn't be a refund.
But really, it's not Disney's fault if you don't use all the days of your ticket package, so there's no reason for them to refund. They provide you with the opportunity to use them, it's up to you to do it. If you choose not to - whether because you've arranged a schedule that doesn't allow for it or illness or whatever - it's got nothing to do with Disney. They've provided the park for you, you purchased the tickets, it's not their fault if you don't use them.
Harsh, but true.