My camera displays "No SD card" when I do have a

See if camera electronics can be reset. Contact the manufacturer for this procedure. If nothing can be done to restore camera to factory defaults then the electronics are fubar. May not be cost effective to repair.

Try to delete files / format the card in a PC./

Look at your memory card. SD 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 camera supports SD HC, multimediacard and SD memory cards, is that card of a different type? you will get this problem if the card is of too large capacity too, your camera ,might have an upper limit for supported memory capacities.

Find a solution, you can have a try:

1. SD Card out
2. Battery out wait 10 seconds
3. Battery in wait 1 minute (this extra time was the key to getting this sequence to work for me)
4. Power up take a photo, power down (you have about a three second window before it goes into Tel mode)
5. Wait 1 min

6. Power up (NB still no SD card)

At this point camera appears to be working stays in normal mode with --- displayed because no SD card is inserted.

Also interestingly plugging a video output cable into HDTV output socket makes camera go to Tel mode AND when you unplug it camera goes back to normal.

However plugging the SD card sends camera into Tel mode permanently. On the plus side this 1-6 sequence was repeatable and worked every time.

From this point I tried many combination's of video cables, SD cards, formatted, erased waiting....then came the USB cable!

7. Connect USB cable to computer (NB still no SD card installed)

8. Insert SD (Computer should detect card and any photos taken should be viewable)

9. "Eject" Camera from Computer USB

10. Disconnect camera from USB (should power down by itself)

11. Power up Camera, Woohoo! it works again!

BTW, if you don't know how to connect GoPro to TV, you guys can check the following guide for help.

Guide: How to Connect GoPro to TV

SD and SDHC cards fit the same slots, but they are slightly different electrically. Many cameras won't work with SDHC (high capacity) cards. SDHC is not backwards compatible.

If your manual doesn't specifically mention SDHC cards or memory card size bigger than 2GB, then the camera almost certainly won't work with SDHC. My Lumix won't work with anything larger than 1GB SD.

You didn't specify the make and model of your camera, but from what you do say I suspect it uses SD cards. Your 4GB card is actually an SDHC card. While it fits into the slot, it's electronically incompatible. Try using an SD card 2GB or smaller.

There are no 4GB SD cards. "SD" cards larger than about 2GB are actually SDHC cards. SD and SDHC cards fit the same slots, but they are slightly different electrically. Many cameras won't work with SDHC (high capacity) cards. SDHC is not backwards compatible.

Assuming this is a blank card. The card may have to be formatted. This uaually found under menu>tools>format.