Back in the day, we routinely repaired damaged circuit board traces with insulated, solid, 30 AWG wire-wrap wire. Short breaks could be repaired with uninsulated lengths of stripped wire, and longer breaks (like an entire track vaporized!) could require 24 AWG solid wire and also a spot or two of glue to hold the repair in place against the board.
In either case, you need to clean the ends of the remaining traces down to bare copper, as
@73's de Edd mentioned in his post #3, and tin them with solder before "tacking" the repair wire in place. But the main thing you need to know is WHY the traces failed. You absolutely
must find and fix that problem FIRST, as
@Bluejets mentioned in his post #2.