I have an olympus d-490 zoom every time i put the card and open the lens lcd show like T sign and yes or no, if you press yes shows card error, if you press no naothing happened

Look at your memory card. SD and SDHC cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

your computer see the card just the same way it see any
other drive it shows icons to represent the files

Thats because thers no card in the camera put
the card in the camera

Did you install the sofrwree bundled with the
camera it might have a viewing & editing program
on the cdrom

Try to format your card in a external pc device, then test if work in your camera.

At this point it sounds like you will need to format the memory card. This will permanently erase all the data from the card and then you will be able to use it again. To format the card: Press the Ok button - right arrow to Mode Menu - down arrow to Card tab - right arrow to card setup - right arrow to format option. You will see format yes or no. Choose Yes and press ok. This will clear the card and it can be used again. Make sure you download all images prior to formatting as once the card is cleared all data is lost.

The following blog outlines some repair options for a lens error:

http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html

Olympus offers a FishEye lens (FCON-02) for use with the D-340L/340R and the D-400/450/460/490 Zoom digital cameras.

The D-400/450/460 and 490 Zoom can use a 2, 4, 8, 16 and 32 MB SmartMedia card. In addition, the D-450/460/490 Zoom can also use 64mb SmartMedia cards.

The D-400/450/460 and 490 Zoom can use a 2, 4, 8, 16 and 32 MB SmartMedia card. In addition, the D-450/460/490 Zoom can also use 64mb SmartMedia cards

The D-490 Zoom shares the following features with the D-460 Zoom: •Olympus 5.4mm to 16.2mm (equiv. to 35mm to 105mm on a 35mm camera) lens: all-glass, 8 element, 6 groups, 2 aspherical lenses •Automatic TTL focus system •Macro mode allows the camera to auto focus as close as 8 inches •Automatic aperture selection: f2.8 to f8.0 wide, f4.4 to f12.6 tele •3x image magnification inspection mode •Panorama mode: Allows multiple pictures to be "stitched" together to create wide views •NTSC video output to TV •12-second self-timer •8MB SmartMedia card included •Built-in, pop-up intelligent flash: Auto low & backlight, red-eye reducing, off, fill-in, slow-sync •Automatic white balance control or 4 manual settings (daylight, cloudy, tungsten light, fluorescent light) •Automatic ISO sensitivity or manual selectable ISO settings •Uses 4 AA size batteries. AC Adapter is available as an optional accessory In addition, the D-490 Zoom has the following functions and features: •2.1 megapixel resolution (1600 x 1200) •Sequence mode - up to 5 shots in HQ and up to 45 shots in SQ mode (1.3fps) •Motion picture mode - up to 60 seconds of QuickTime movie (.mov) format (w/o audio)

The D-400/450/460 and 490 Zoom can use a 2, 4, 8, 16 and 32 MB SmartMedia card. In addition, the D-450/460/490 Zoom can also use 64mb SmartMedia cards.