In some occasions the wire is broken or came loose at the terminal, try to reflow the joint with a good amount of solder.
if that doesn't work you'll have to dismantle the base, test again and if the windings turn out to be in good order, make a new terminal base and reattach the wires
If the winding is open internally it would be much harder to repair, afaik these transformers aren't the easiest to wind
