Your SD/SDHC memory card is been disappeared and no longer been detected or wants to be formatted suddenly, even though seconds ago the card is still working properly?
Be sure the controller of your card is physical damaged, no software can help. The only way to get the data/photos back, unsolder the memory chip, directly dump their raw data with a programmable chip reader and convert it to readable data. Their are only some specialists on earth, they are able to do this complicated procedure.
See also: Reasons for data loss, when can data/photos be saved

Formatting is required? The controller of the memory card is not in the position to inform the PC operating system about the characteristics of the memory card. Therefor the PC assumes, the memory card is not formatted and requests formatting. One could now think, the memory card problems are solved by formatting, unfortunately that does not work due to the damaged controller. Try it out, the PC will communicate, that a formatting is not possible. Finally this is then also a clear proof that any kind of software, also special formatting or rescue software!!, no more can access to the memory card.

This article is licensed under the gnu free documentation license. It uses material from the wikipedia article Secure Digital card The authors of that article are listet here.

Secure Digital (SD) is a non-volatile memory card format developed by Matsushita, SanDisk, and Toshiba for use in portable devices. Today it is widely used in digital cameras, handheld computers, PDAs, Media Players, mobile phones, GPS receivers, and video game consoles. Standard SD card capacities range from 4 MB to 4 GB, and for high capacity SDHC cards from 4 GB to 32 GB as of 2008. The SDXC (eXtended Capacity), a new specification announced at the 2009 Consumer Electronics Show, will allow for up to 2 TB capacity cards. The format has proven to be very popular. A change in the format, however, while allowing capacities greater than 4 GB (SDHC), has created compatibility issues with older devices that cannot read the new format. The fact that SDHC format cards have the same physical shape and form factor as the older format has caused considerable confusion for consumers. SDHC cards require SDHC-capable device firmware generally not found with older devices.
Design and implementation: SD cards are based on the older MultiMediaCard (MMC) format, but have a number of differences: The SD card is asymmetrically shaped in order not to be inserted upside down, while an MMC would go in most of the way but not make contact if inverted. Most SD cards are physically thicker than MMCs. SD cards generally measure 32 mm × 24 mm × 2.1 mm, but as with MMCs can be as thin as 1.4 mm if they lack a write-protect switch; such cards, called "Thin SD", are described in the SD specification, but they are non-existent or rare in the market as devices that would require a thinner card are usually utilising the smaller (and thinner) versions of SD: miniSD or microSD. The card's electrical contacts are recessed beneath the surface of the card, protecting them from contact with a user's fingers. SD cards typically have transfer rates in the range of 10-20 MB/s, but this number is subject to change, due to recent improvements to the MMC standard. Devices with SD slots can use the thinner MMCs, but standard SD cards will not fit into the thinner MMC slots. miniSD and microSD cards can be used directly in SD slots with a simple passive adapter, since the cards differ in size and shape but not electrical interface. With an active electronic adapter, SD cards can be used in CompactFlash or PC card slots. Some SD cards include a USB connector for compatibility with desktop and laptop computers, and card readers allow SD cards to be accessed via connectivity ports such as USB, FireWire, and the parallel printer port. SD cards can also be accessed via a floppy disk drive with a FlashPath adapter.
File system: Like other flash card technologies, most SD cards ship preformatted with the FAT or FAT 32 file system. The ubiquity of this file system allows the card to be accessed on virtually any host device with an SD reader. Also, standard FAT maintenance utilities (e.g. ScanDisk) can be used to repair or retrieve corrupted data. However, because the card appears as a removable hard drive to the host system, the card can be reformatted to any file system supported by the operating system. SD cards of size 4 GB and lower can be formatted to either FAT16 (4 GB card can be formatted to FAT16 only with 64k clusters) or FAT32 file systems. Cards 8 GB and larger can only be formatted with a file system that can handle these larger storage sizes, such as FAT32. Defragmentation tools are used on hard disks to optimize the file system access speed. On an SD card, this is pointless, as any block can be accessed as fast as any other. Doing this will wear the card out slightly, as a limited number of writes can be made before failure.
SD Speed Class Ratings: SD Cards and SDHC Cards have Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum write speeds based on "the best fragmented state where no memory unit is occupied":

• Class 2: 2 MB/s - 13x
• Class 4: 4 MB/s - 26x
• Class 6: 6 MB/s - 40x