There are two s9920 in the past,s9920 mtk6577 and s9920 mtk6572. The manufacturer has no old touch screen for S9920 MTK6577 Now.
If your s9920 is like the following picture
The flash steps are as follow:
1. Install driver on your PC: https://mega.nz/#!osgC1IIC!4SITuG6yqkgizdiO-zElzsUjxEPeZxjUZciIiZDTVLM ;
2. Download the flash tool here (https://mega.nz/#!l4hlmQpK!Q4rQtsdFkawT1vwX2aUS-wFLsZ5A85YAOlwTVGkP-18), and choose “MT6577_Android_scatter_emmc.txt” in the ROM we provided, set the flash tool like that
3. Put the battery in your S9920,use usb cable to connect the phone with your PC.Then wait few minutes until download ok