Scheduled listings can fail to launch for a number of reasons. Provided the original reason for the failure is addressed, you can then reschedule the listing.
How to Reschedule a Failed Listing:
The listing entry will be moved from the Failed category to the Scheduled category.
NOTE: If a rescheduled listing fails to launch again, try using the "Sell Similar" action on the failed listing and reschedule a new listing.
If this new listing launches successfully, delete the failed listing entry.