mareregu ,
Here is a thread discussing about editting the windows registry to disable the write protect.
If your player can be detected by the MP3 Utilities Upgrade Tool, you will need to try various firmware dumps in the downloads section for your screen size to recover your player.
Regarding the data, can you see your player's drive appearing in explorer? If so, you can retrieve your data out. If not, go through the process of recovering your player. But you might end up not being able to retrieve the data from the memory chip. As in some cases, you will need to format your player before it can accept firmware dumps.