When a card is inserted, Windows reads its first sectors looking for a partition table and a boot record it understands: FAT32 on an SDHC card, exFAT on an SDXC card, occasionally NTFS on a card someone formatted on a PC. If what it reads is not a file system it knows, or is a FAT32 or exFAT header with a damaged table behind it, it reports the volume as RAW in Disk Management and raises the dialogue. The photographs, the video, the documents are in the data area behind the tables, and the dialogue has not touched them. Nor has the card lost them; it is the map that is damaged, not the territory.
The commonest cause is an interrupted write. A camera, a phone or a dashcam writes a file's data and then updates the allocation table and the directory entry that point at it, and a battery that dies between the two, or a card pulled out, or a phone that crashes, leaves the tables inconsistent. exFAT, used on every card over 32GB, keeps an allocation bitmap and a single file allocation table, and a tear in either is enough for Windows to refuse the volume. The bench reads the surviving entries and chains, rebuilds the tables on an image, and carves by signature whatever the entries no longer point at. The files come back with their names where the entries survived and with their own dates where they did not.
Two other causes arrive often enough to mention. A card from a Steam Deck, a Raspberry Pi or a Linux box carries an ext4 file system that Windows simply does not read; it is not damaged, and it reads on any Linux machine. And a card whose controller is failing returns inconsistent data from one read to the next, so that Windows sees a header one moment and nothing the next; that card is imaged in short passes and, if it will not hold still, read through its test pads.
What a format does depends on which format. A quick format, the default in Windows and the only kind most cameras run, writes new, empty tables and leaves the data area alone; the SD Association's formatter manual says the data still remains in the card and may be retrieved by using a data recovery tool, and the bench retrieves it routinely. A full format, the box left unticked in the Windows dialogue, writes zeros across the whole card on Windows Vista and later, as Microsoft's knowledge base article 941961 documents, and nothing survives it. The SD Association's own formatter has an overwrite option that does the same. Nobody who wants the pictures back should run either, and nobody should run chkdsk, which on a RAW volume refuses anyway and on a damaged one repairs the wrong thing and writes the repair back.