I am not able to switch on my player.i have tried to reset it but that was not helpful.i have formatted it once it was not helpful too. so what should i do now.

To reset your Sansa Mp3 player. 1. Slide and hold the Power switch up for approximately 20 seconds. 2. Release the Power switch. 3. To turn the player on, slide the Power switch up then release instantly.
If that does not get your player working again, try and Format to clear any corrupt files that may be present.
You will lose all your music - sorry. For the Sansa Clip: 1. From the Main Menu, in the player -> select Settings -> Format. 2. Select Yes.
You can also format using Media Player if you have unfrozen your player. 1. ->start Media PlayerIf you have Media Player 10 --- Connect the Sansa player to the PC in MTP (See next step to change to MTP mode) .
1. Turn the player OFF. 2. Slide the Hold switch down to Lock (orange color showing). 3. Press and hold the center button while connecting the player to the PC with the USB cable. once you have done that...
Click on the Sync tab.(be sure your player shows in the pull down menu)Click the pencil icon on the upper right corner of the window.Click OK to start formatting. Now if you have Media Player 11---Click the Sync tab.On the left panel, look for the device. It is usually the last device listed.Right-click on the device and select FormatClick OK to format.

To reset your Sansa Mp3 player.1. Slide and hold the Power switch up for approximately 20 seconds. 2. Release the Power switch. 3. To turn the player on, slide the Power switch up then release instantly. If that does not get your player working again, try and Format to clear any corrupt files that may be present. You will lose all your music - sorry. For the Sansa Clip: 1. From the Main Menu, in the player -> select Settings -> Format. 2. Select Yes. You can also format using Media Player if you have unfrozen your player.1. ->start Media PlayerIf you have Media Player 10 --- Connect the Sansa player to the PC in MTP (See next step to change to MTP mode) . 1. Turn the player OFF. 2. Slide the Hold switch down to Lock (orange color showing). 3. Press and hold the center button while connecting the player to the PC with the USB cable. once you have done that... Click on the Sync tab.(be sure your player shows in the pull down menu)Click the pencil icon on the upper right corner of the window.Click OK to start formatting. Now if you have Media Player 11---Click the Sync tab.On the left panel, look for the device. It is usually the last device listed.Right-click on the device and select FormatClick OK to format.

try resetting the device first you should slide the Power switch up and hold it for approximately 20 seconds.
then. release the Power switch once the device is powered down.
Turn the device back on.

if that does not work then download and install sansa firmware updater from this link
http://kb.sandisk.com/app/answers/detail/a_id/156/kw/firmware/r_id/101834

if your problem is not solved after this then format your device.FORMATTING WILL ERASE ALL YOUR DATA SO ITS ADVICED TO BACK UP YOUR DATA BEFORE FORMATTING
From the Main Menu, select More > Settings/Options > System Settings > Format.

To reset your Sansa Mp3 player.1. Slide and hold the Power switch up for approximately 20 seconds. 2. Release the Power switch. 3. To turn the player on, slide the Power switch up then release instantly. If that does not get your player working again, try and Format to clear any corrupt files that may be present. You will lose all your music - sorry. For the Sansa Clip: From the Main Menu, in the player -> select Settings -> Format. Select Yes. You can also format using Media Player if you have unfrozen your player.1. ->start Media PlayerIf you have Media Player 10 --- Connect the Sansa player to the PC in MTP (See next step to change to MTP mode) . 1. Turn the player OFF. 2. Slide the Hold switch down to Lock (orange color showing). 3. Press and hold the center button while connecting the player to the PC with the USB cable. once you have done that... Click on the Sync tab.(be sure your player shows in the pull down menu)Click the pencil icon on the upper right corner of the window.Click OK to start formatting. Now if you have Media Player 11---Click the Sync tab.On the left panel, look for the device. It is usually the last device listed.Right-click on the device and select FormatClick OK to format.
Try my tip posted here -- > http://www.fixya.com/support/r4055689-download_mp3s_player <- copy this address into a new window.

First reset yours by the Back button;

If not solved;

Reset again by the button, the On the Computer by Fat32 Format, and then Copy the Initial Files that were on your MD when you Bought;

Good luck

I think I can help.  I had a similar issue where the recovery tool would recognize my mp3 but the firmware would not.  This is what I did:    Turn on your Zen, Holding the power switch in the on position. While holding the Power switch on (very important), Reset the Zen by inserting a small object in the Reset hole on the bottom of the Zen (I used an earring). You will see a menu: Clean Up, Format, Reload OS/Firmware, Reboot. I decided to go down the list until something worked.  I ran Clean Up first and that didn't work for me, so I tried Format.  Note that this will remove all of your data.
Once Format runs, Reboot the MP3 player and plug it up to the computer. Run MP3 Recovery Tool. At this point, the firmware recognized my MP3 and installed successfully. Once installed, my computer recognized my Zen.

This should help you right here: Detach the player from the PC and turn the unit off. Then slide the power switch towards the power icon and hold the switch. Push the end of a pin-like object (for example, a straightened paper clip) into the reset hole, press gently and remove. Release the power button when the recovery mode appears. Select format (all) and select yes to format the player. After the player has finished formatting, select reboot. Then retransfer the tracks to the player as doing the format will erase the whole player.

I had this same problem on my sansa and tryed the previous solution with no luck. Out of frustration i email the sansa technical support. Try these steps to format the player: -Turn on the player and access MENU > SETTINGS > USB > MSC - Once the player is set to MSC mode, reconnect it to the computer and open the My Computer window. - Once you see the Sansa icon in the My Computer window, right-click it and choose FORMAT - In the Format window, choose FAT 32 and make sure that Quick Format is NOT selected, then choose START -Once the format has completed, disconnect the player from the computer to allow it to refresh. If you plan on using Windows Media Player to transfer files, return to the USB menu and set the player to MTP mode. Otherwise, leave the player in MSC mode and you can now resume transferring files. Formatting your player will deleate all files but you can putt them back on!!! Best of luck!