Any idea how to contact the Developer????

Every software license I have ever read includes a clear statement that the developer can terminate their support for your license at any time they chose to. Software licenses also include clauses stating that your license entitles you to use the software “as is” as well as “as available”. There is zero chance at all you will get a refund, since nothing in the licenses guarantees the software will be available nor supported for any defined period of time.

Apple - Legal - Licensed Application End User License Agreement

You purchased an app a few years ago, have used it, and now you would like a refund? Sounds a little strange to me how you feel you deserve a refund for an old app. However, you are free to search the internet for information if the app does not provide any support information.

Put in the name of the app in a Web search to see If the app developer's website comes up in the search.

Chances are pretty good that you WILL NOT receive a refund. Sorry.

There are many app developers that maybe lone developers, small group of app developers, that dropped support and orphan/abandon their app/s for many different reasons, like didn’t make enough revenue, the company went bankrupt, the developers, like a musical band, split up and/or lost interest in keeping up support for an app, didn't like how much percentage Apple was taking for their app VS what the developer/s was/were making on each sale of the app, etc.

Also, If this was an older 32-bit app that has never been updated in over two years and the app developer didn’t bother to recode the format of the code to a 64-bit version that supports iOS 11, there is nothing you can do.

Also, and I am not certain Apple is admitting to this, but Apple is, once again, covertly and secretly, thinning out older, 32-bit apps that haven't seen ANY type in support in say, the last three years, or so.

There are millions of apps and this happens everyday on the iOS App Store.

You never really own an app on ANY type of mobile or computing device locked into an App ecosystem>

You actually pay rent for the use of a types of apps that need some connective support from a developer.

Not all apps work ths way, but some do.

This is why i haven't updated my iTunes past version 12.6.3, so I can still save ALL of my iOS apps locally in case an App disappears from the iOS App Store or is no longer supported, I still have a backup copy of the discontinued app.

Good Luck to You!.

You might want to go back and read the Terms for iTunes and the App Store, which will explain this to you, and you will see you are not entitled to any compensation; from the developer or Apple.

And your computer comparison is completely different. That is hardware you have bought. The store stopping to carry that has no affect on your device. An app is nothing more than a license to use the software. Comparing oranges and bananas.