When I put music on my Micro Sd card I can't play it.

From your description, you seem to have bought a regular SDHC (secure digital high-capacity) card. A Sansa Fuze can only accept micro SD or micro SDHC cards. For buying a new card, I would suggest this card from newegg.com. As for other things you mentioned: No, the card you bought is not meant for cameras only, the only reason your device uses micro SD/SDHC cards is because it is a smaller device. The 4 on your card signifies that it is class 4 which is the card's speed classification.

Hello,

For the Sansa Fuze there's a manual available in pdf format on the Sandisk support site:
http://mp3support.sandisk.com/sansa/UserManual/FUZE/fuze_userguide_en.pdf
Save this file to a location on your computer for later use.

When you explore "My Computer" the micro SD card with x GB memory, should be available as an extra external drive.
This drive will show up as an extra drive letter with a total capacity of x GB .

You need to visit SanDisk and upgrade your MP3 firmware for Slot radio cards!

place the blank card into the SanDisk player
go to SETTINGS press "enter"
go to SYSTEM SETTINGS press "enter
go to FORMAT press "enter"
it will ask "are you sure you want to format this device"?
select YES

dowload songs to REMOVABLE DISK drive F, at least that is what my PC assigned it to. You will overload your MP3 PLAYER if you continue to download to the Sanza Drive.

Hope this helps.

Sansa C240 can only read SD cards that are NOT SDHC - that means it can only read up to a 2gb Micros SD card.

Make sure your usb mode is msc plugin your sansa and go to my computer click on Sansa folder and you should see your removable disk this is your expansion card

Sorry, it doesn't work that way. You can use a separate card reader to put files onto the microSD card. When the card is installed into the Sansa, the Sansa will see the additional music.

It's pretty simple really. To actually get music on your micro sd card you have to put it into an adapter and connect it to your computer. Then you have to put the music on the card seperately. Then plug it into your sansa and it will recongnize the songs and play them like normal

There are 3 ways to solve your problem, but all of them are rather kludgy. This is an old player and the integration of the microSD card is not done very well. I believe with the newer players these sorts of issues are not problems. Anyway, here are your 3 possibilities:
1) You can load your music directly onto the card before you put it into the player. Most cards come with an adapter that lets them fit into slots that are for regular SD cards. So if your computer has a slot for an SD card (or if not, you can plug the card into a card reader and then plug the card reader into the USB port on your computer) then you can copy and paste mp3 files onto the card. This is a drag because you can't use Windows Media Player to do this, but instead need to open the folder where the MP3 files are and then copy and paste them onto the card. But it works
2) This is slightly easier. Before you connect the Sansa player to the computer go to the settings part of the main menu and then select mode. You should see two choices. One is MTP and this is the setting you want if you are using the player with Rhapsody service. The other setting is MSC and this lets your computer recognize the Sansa player AND the microSD card. Once you have selected the MSC mode, then you can connect the player to your computer. When you look at the drives on your computer, you'll see 2 new drives. One is the Sansa 280 and the other is the microSD card. Once you see those, you can copy and past MP3 files right onto the card (and/or onto the Sansa). Again, you have to go the folder where your MP3 files live and cannot use WMP to do this
3) I haven't tried this, but others say that a free program called rockbox (www.rockbox.org) let's all this work much better. It sounds complicated, as it puts kind of a new operating system on your Sansa and it may not be reversible, so proceed with caution, but some people love it.
Hope that helps

Go to the knowledge base on the Sansa site and find this (chances are you have an SDHC card in an incompatible unit):
Sansa e200 - verify the version of the player.  To check, go to SETTINGS > INFO. 
              
For 01.xx.xx firmware (e200 version 1) - up to 2GB microSD cards 
For 03.xx.xx firmware (e200 version 2) - up to 16GB microSDHC cards 
NOTE: Firmware is not interchangeable. 

Sansa e200R - up to 2GB microSD cards 

Sansa e100 - supports SD cards up to 2GB