lost my standard ringtones.. how do I get them back?

The standard ones should repopulate when the device is restored. Maybe try restoring again? Or, does your device have a file explorer? if not, you could try downloading one, (like ES file explorer) and look around to see if there is a media folder containing those audio clips. Worst case scenario, you can download a ringtone app from the Play Store and it will create a new ringtone/audio directory with some audio clips. Those new clips should then show up in native phone apps like "phone", "clock", etc.