Have you ever sharpened your colored pencil just to have the lead break and then when you sharpen it again the pencil lead break again and again and again until the pencil is almost gone? That usually means that lead in the the pencil barrel is broken but you can fix it, here's how:
1) Prepare baking pan and cover it with any baking paper or aluminium surface
2) Line up the colored pencils on the baking pan
3) Insert the baking pan into an unheated oven and set it to around 250 degrees F
4) Let it run for 2.5-7.5 minutes. The duration will vary from oven to oven, how close you put the tray to the heating strips, and how damaged the pencils leads are.
5) After the 2.5-7.5 minutes have passed, turn off the heat in the oven but leave the colored pencils in until it has cooled back down to about 70 degrees F (about room temperature).
6) Test the pencil by sharpening it to see if the lead is healthy again.
7) If the pencils haven't completely healed after the first bake, go back to step 1 and do it again the process
These steps will fix all types of colored pencils, just remember that pencils with soft leads will melt faster than pencils with harder leads so they will require less time in the oven.