Can't Open Contacts and LFG list (Y)
Tarnished Coast
You could try a -repair of the client. Instructions found via the ‘Support’ link above/below and ‘Search – Repair’.
You could try deleting the GW2 local.dat file.
You could contact the CS Team via the ‘Support’ link above/below.
Submitting an in-game Bug Report will garner no response, as indicated on the Bug Report window.
Good luck.