Time to go shopping first. Find a thread pitch file, metric (?), these are four sided and will have 8 thread pitches. This file maybe hard to find, but I would check at Napa in the KD tool line. If a thead file cannot be found, get a fine needle file set. Use either file to restore male threads. Use a pick or a pocket knife on the female threads. Keep area clean, carefully reassemble using a light oil or grease. If your are working with a flare fitting and it still doesnot seal, find a 'conseal' or conical seal. It is a soft aluminun seal that fits over the male flare, install lubed not dry.