This is a quick trick I used to fix some of my cords that had become hopelessly twisted. It's not a guaranteed fix - but it does a great job at improving the condition. Think of it as laser-tatoo removal without all the pain.
Step 1: It's OK. Help is on the Way - Here's All We Need
The drill can be corded (gasp) or battery powered.
You can actually use almost any tape you want.