Sansa Fuze 8 GB Problem...It's on...But black screen, wont play, wont turn off...Nothing...

I have Sansa Fuze 8 GB, and I have a problem to save my data on the player. I have used it to record and download music and books. I like it very much. But after I download music on the player, it turned black and after I restarted it I had a notification that the memory lack of 92 MB. I connected it with my computer because I could not have not remove file to reduce to gain back memory. I am can not list the resume on the computer even though it is connected and the battery is full. I tried to put extant memory 2 GB and 8 GB Micro SD Scan Disc and nothing works. I tried to pull on/of button and held it for 20 seconds and nothing happened. What can I do to have it work properly and save my data?