TestDisk is a free and open-source software tool designed to recover lost partitions and repair non-booting disks. It supports various file systems, including FAT32, NTFS, and ext2/ext3/ext4, making it versatile for different operating systems like Windows, macOS, and Linux. The program operates through a command-line interface, which may seem daunting for some users. However, it provides step-by-step guidance to help recover data effectively. TestDisk is particularly useful for those who accidentally delete partitions or experience disk corruption, offering a reliable solution for data recovery.