The (often extracted as NVRAM.bin , nvdata.img , or nvram.img ) is a binary image of this partition. It is critical for baseband functions, Wi-Fi/Bluetooth MAC addresses, serial numbers, and IMEI numbers.
If you created a SP Flash Tool backup before the corruption, you are in luck. That backup file is the most reliable source. Method B: Download a Stock NVRAM Image mt6768 nvram file