Apple released iOS 8.1.2 which fixes a bug for missing ringtones on your iPhone, iPad, or iPod touch.

Here is how to restore those ringtones -  

1- Update your device to iOS 8.1.2
    Go to  Settings - General  - Software Update - Run the update

2- If you purchased your Ringtones on your iPhone, iPad, or iPod  
    touch and never synced them to your MAC computer you can still
    restore them - just open Safari on your Iphone and enter this url

     itunes.com/restore-tones

3- Sign in with your Apple ID

4- Tap Restore

5- Tap Done

6- You will get notification on your Device when it is ready
   - when you get it click download

7- to see if they came back - go to setting on your Iphone and click
    sound then ringtone to see if the missing ones are there.