I no longer have access to the device used for double authentication (cell phone or U2F key lost, sold or damaged).

Use one of the recovery codes provided to you when you activated double authentication (TOTP).
If you have lost those recovery codes or if your U2F device is lost/broken, open a support ticket at the bottom of this page and then reply to our automated email and attach the following form, duly filled out, signed and accompanied with proof of ID.