You are not required to report income that does not belong to you. If you know you did not sell anything on Facebook or the only items you sold were personal use property that was sold for less than you purchased it for, there is nothing to report.
If you remember selling any single item for a profit, it must be reported on your tax return. This would be similar to a yard sale of sorts.
If you received an erroneous 1099-Misc, you have several choices: