This instructable will help you salvage your headphones that snap
above the earpiece where the plastic is thin.

Step 1: This Is the Spot Where the Headset Broke

Here is your headset where the plastic has broken just above the earpiece where the plastic is thinnest

Step 2: Cutting

Next, take a razor knife and cut out the bottom of the headband just above the break.

Step 3: Finished Cut

Here's what it looks like from the bottom when cutting is done.

Step 4: More Cutting

Now cut the lower stem so it is angled like the headset slot and test for a tight fit.

Step 5: Gluing Together the Two Pieces

I decided to glue together the two pieces. I tried superglue and
epoxy, but neither worked. I had some JB Weld, so I used that
and it worked great. It is rock hard. This stuff is only about $5 @
Lowes and a little goes a long way. You mix equal amounts together
with a stick and then put it on the part you want joined.

Step 6: Putting It Together

put a spot of JB in the upper slot of the headband, then slide in the
lower part and smooth the JB over. Allow to dry overnight and sand
it if there is any globs sticking out. My repaired headset is hoding a
month later. It no longer adjusts, but beats throwing it out and paying
$20 for a new one!