Why are my default ringtones missing OS6 9800?

i have reset my 9800 than my default ring tones missing.. how i get back

You lost the settings, or lost the ringtones from the phone?

If you need the replacement ringtones, you can download from here: Missing those classic ringtones from your old BlackBerry? Here's how you can get them on BlackBerry 10 | CrackBerry.com
They're actually the OS7 version, which include the OS 6 tones, plus a few more. All work on OS 6.