The error code 67 referS to the lit up LED display showing the problem. You have a evaporator motor problem inside the freezer that may have either failed or is jammed up with ice. You will need to pull the freezer drawer and shelves out to gain access to the back wall of the freezer. Remove the panel and see if any ice has built up and around the fan. If it has, clear it out and reinstall back. Pull the plug to clear the error code and see if the fan starts blowing again.
Also check the fan by turning the fan blade with your finger while it's still in the freezer. If it doesn't turn at all or it's hard to turn, it's possible that moisture got inside the motor and will need to be replaced. The part number is
4681JK1004A.
LG
4681JK1004A Mtr. Assm.,ref Fan,
AP4439225

Hope this helps.