If you previously had TPControl installed on the device, or you are logged into an AppleID that has previously downloaded it, go to the "Purchased" tab of the App Store application and you should find TPControl available to download.

Failing that, launch Safari on the device and browse to the following URL: https://itunes.apple.com/us/app/tpcontrol/id348715945?mt=8

If you use a different store to download your apps, then replace the "us" in the url with your region e.g Australia = "au", Singapore="sg" etc. To find the relevant abbreviation, go to https://www.apple.com/choose-your-country/