Memory Card my camera displays "this card cannot be used" or "Warning! this card cannot read" when it was working fine for the past few months.. I don't know what's wrong with it, the manual says what to do, but when I do it, it doesn't work.. I can't take any pictures with my memory card in now.. but without the card I can take up to five pictures.. which is dumb because it was working fine before.. and i did nothing wrong to it..help?

Unfortunately Flash drives / Memory cards once corrupted are pretty much useless... But, I would recommend you format the memory card from a Linux based PC, If you are lucky, you may be able to use the card again (Windows is a B****).
Moving forward, keep in mind that the card should not be filled to capacity (Meaning: a few MBs of free space should always be available). So next time when you are taking photographs make sure that you don't exceed 90% capacity of the memory card.

Try another sd card if it works the camera warning is right

Try to use your card in a clean computer and run a virus or malware test on it. Make sure that the card has no unwanted hidden folders that may contain virus files unblocking the card from being accessed by your printer.

It wants you to format the card in the camera. This will erase the card so download any pictures on it first using a card reader if necessart.

Have you tried another brand of memory card ?
Try a memory card from a friend that has been used for a while. If it locks up with other cards then you have problem with camera. Check if needs to be set to read from memory cards above certain sizes ?

I think u have to format your memory card through ur camera setting option..

I would try another card first, before doing anything else.  If you have been using just one card for 6 months and using it a lot, it could be corrupted.   It's best to always have a back up of at least one card anyway, and they have come down in price considerably.
If my suggestion and McComijohns's don't work, I would consider taking the camera in for repair.   It is NOT a good idea to mess around too much with the inner workings of the camera.  You could cause a lot of damage and it won't be covered under your warranty.  Good luck.

I had exactly the same problem with a 2 year old LX-1. The card worked fine on the computer, formated no problem but would not work in the camera.
I took a can of air and used maybe 3 one second bursts to blow out the card slot. Card immediately started working.

-prmolina

I would try another card with the camera to see if there is a fault in your camera or the USB cable. If the other card works fine, then there nay be some compatibility issues with the M type XD card in your camera. Just for reference: I have several older FujiFilm digital cameras that I still will not use the newer style cards with. Newer meaning the 'M' and 'H' series cards. Fuji says they will work fine, but I'm always leery of newer techno gear being 100% compatible with older stuff.

Here is a link to Fuji's memory card chart: FujiUSA

Hi there, please check with the Nikon Dealer the 4G card compatibility issue, maybe the card is too big for your camera. Best regards, Arpi