Music player deleted my songs and I cannot reload

I am having a couple of issues with my phone.  I did a search and couldn't find anything that helped, so I am posting.  Sorry if this is a duplicate, but I did try to search.

I had about 70 songs on my Instinct.  One day, they just completely disappeared. 

Now, I am unable to load any music onto my player.  I have used the Sprint Media Manager to try and load new songs on there, but with no luck.  The thing is, if I open up the card files in Windows Explorer or Media Manager, I can see that those songs are on there.  But my phone does not recognize that there is any music there at all.  It shows 0 songs available. 

Not sure if this is relevant, but there is a folder of a Paul Simon CD on there that I have tried several times to delete.  Every time that happens, it says that folder is not accessible because it is corrupted and unreadable.  I cannot delete it or anything; it's just there, staring defiantly in my  face.

Any ideas?  Should i try a new card maybe? 

This might be a dumb question, but how do I reformat?

It worked!  Thanks a million!