If the player was set to the default USB connection Auto Defect, the player could connect in either MTP or MSC modes when you originally transferred the the files to the player. Since most everybody transfers a few songs or albums at a time and not all at once, it is very possible you have a number of songs transferred in both modes.
The player will see and play these files without incident, but your computer can only see files that were loaded onto the player while it is in the same mode. So if your player is now connecting in say, MSC mode now you will only be able to see and access songs that were transferred in MSC mode. Files transferred while the player was connected in MTP mode will be invisible. And vice-versa.
Try this . . . copy those songs/files that you can see back to your computer. Disconnect the player and shut it off. Now press and hold the REW button while plugging it back into your computer. This ‘forces’ MSC mode. Continue holding the REW button until the player starts up and is recognized by your computer. I suggest this as the ‘Auto’ setting defaults to MTP mode, and this is what we see most often here. So forcing an MSC connection may reveal your other ‘hidden’ songs.
In Windows Explorer, the player will be recognized in MTP mode if it is listed a “musical (or audio) device”. If it comes up under Devices With Removable Storage and is shown as 2 additional and separate drives, each with its own drive letter (like F: and G: ) then it is connected in MSC mode.
See now whether the song files you can see are different than the other ones you previously saw and copied back to your computer. If so, the player was set to MTP or (Auto) before and now you have access to the remainder of your songs so you can easily copy them to your computer.
You can now format the player via Windows by right-clicking on the player’s drive letter (in Explorer). Don’t use the ‘Quick Format’ option. This will erase all user-added content and may solve the white screen issue. You can then manually select the USB connection mode (after un-plugging and MSC preferred) and transfer, or copy all your music back to the device.
If the white screen issue persists, then connect again in the way described above and manually re-apply the firmware. You can find the latest firmware version here, along with manual installation directions. Don’t download and use the Updater. If the format did not solve the white screen issue, this might.
Note that there are 2 different firmware versions for the 2 different hardware configurations in this model. Normally, you have to know which version you have so you download, un-zip and install the correct one for your player. However, with the white screen, you have no way of identifying whether you have a v1 or v2 player. So try one (doesn’t matter which) and if it works, fine. If not, try the other one. If it is the wrong firmware for your player, it won’t blow up or catch fire or anything like that; the player simply will reject it, so try both.
Hopefully this will help.