My purchased ringtone won’t work

Check here :

Redownload ringtones purchased with your Apple ID

1. Go to Settings > Sounds & Haptics.
2. Under Sounds and Haptic Patterns, tap any sound.
3. Tap Download All Purchased Tones. You might not see this option if you already downloaded all the tones that you purchased or if you haven't purchased any tones.

To make and/or use a song as a ringtone, you must first make that song suitable for a ringtone.

See this Apple article:  Create and manage ringtones

Create and manage ringtones - Apple Community

If you have bought a ringtone, see -> Use tones and ringtones with your iPhone, iPad, or iPod touch

Use tones and ringtones with your iPhone or iPad - Apple Support

• redownload ringtones purchased with your Apple ID

If you have received an invoice from Apple, on every invoice from the Apple Store and/or iTunes Store always states what you have purchased (and/or concerns a subscription) and the amount.

Tap on Report a problem on the invoice.

Or try to ->  Request a refund for apps or content that you bought from Apple.

Request a refund for apps or content you've bought from Apple – Apple Support (UK)

If you have requested a refund, you must wait until Apple has approved. Then you will receive a message from Apple.

Refunds are not guaranteed. For more information, see the Terms & Conditions.