To reformat or re-flash a TWRP installation, follow these steps:
1. Backup your data: Before making any changes, it's important to back up your data, including internal storage and external SD card. You can use TWRP's built-in backup feature or a third-party app like Titanium Backup.
2. Boot into TWRP: Power off your device and connect it to your computer. Then, boot into TWRP recovery mode by using an ADB command: `adb reboot recovery`.
3. Create a backup: In TWRP, create a backup of your current ROM to avoid any data loss during the process.
4. Wipe data: Go to 'Wipe' and select 'Advanced Wipe'. Choose 'Dalvik Cache', 'System', 'Data', and 'Cache' partitions. Swipe to confirm the wipe.
5. Flash TWRP: Download the latest TWRP image for your device and copy it to your device's internal storage or SD card. In TWRP, go to 'Install' and select the TWRP image file. Swipe to confirm the flash.
6. Flash ROM: Download the ROM you want to install and copy it to your device's internal storage or SD card. In TWRP, go to 'Install' and select the ROM file. Swipe to confirm the flash.
7. Reboot: Once the ROM is flashed, go to 'Reboot' and select 'System'. Your device will restart with the new ROM installed.
8. Set up: After the device boots up, follow the setup process, including setting up Google account, restoring apps from your backup, and configuring settings.
Remember to always backup your data before making any changes to your device. This process will restore your device to factory settings, so be sure to only proceed if you are comfortable with this outcome.