Your options are:
* Replacement Rear Window: This is the most common and usually most effective solution. You'll need to find a replacement rear window from a salvage yard, a glass shop, or an auto parts store. This will involve removing the old window and installing the new one, a job best left to a professional auto glass installer. The cost will vary considerably depending on the source and the installer.
* Repair Kit (Limited Success): Some kits exist that claim to repair defroster lines using conductive paint or tape. These are generally considered a temporary fix at best and rarely provide a fully functional repair. The repair might look OK, but the conductivity may be poor, resulting in uneven heating or failure. These kits are more likely to be useful for small breaks than extensive damage.
In short: While some DIY approaches *exist*, they're typically unreliable. Replacing the entire rear window is the only truly effective way to fix a broken rear defroster element. Trying to patch it yourself may lead to further damage or a poor outcome. Get a professional quote from a reputable auto glass shop to determine the cost and best approach for your specific situation.
