Sansa m240 - won't download OR delete songs

I have had the Sansa m240 player for over a year and have had no problems with it until recently when all of my 130 + songs got lost for some reason. So after that, i downloaded more songs. Now i am unable to delete any of them or redownload all the songs i lost! I want to delete a few songs on my Sansa m240 but when i click on the icon in My computer, it shows that there is nothing there! yet, when i unplug it, the player shows 31 songs in it. Also, i tried to download more songs onto it but i was unable to do so for some reason and a message came up saying "windows has encountered a problem with the player". HELP!