For some reason, my Sandisk Sansa e250 MP3 player was stubbornly refusing to acknowledge the music that I was copying to it. I tried just about everything I could think of short of formatting the device to get it to see my folders in the Music folder. My device has the latest version 1 firmware upgrade, and I have tried to use both MSC and MTP mode to copy folders to the device, all to no avail.
Finally, I found out that I could force the device to do a database rebuild by doing the following steps, which should work on any Sansa e200 series MP3 player with the version 1 firmware: (WARNING: Please do not do this if you are worried about making your device inoperable. There is always a risk that this will happen when you start futzing with the system files.)
- Go into the Settings screen and scroll to USB mode, and set it to MSC
- Connect the device to the computer
- Once the device mounts as a drive on your computer, browse to the device, look for the System folder, and the Data folder in that folder
- Delete the file called PP5000.DAT
- Disconnect the device
Once you disconnect, the device will restart, and it should refresh the database. If you prefer MTP mode, make sure to go back into the settings to change it back.