How do I fix this?

My phone - Sony Ericsson W350 came with a perfectly working Sony M2 Memory card - 512MB. I put quite a few songs on 40 something songs. I dropped my phone on my laminate floor, and everything came out of the phone (battery, simcard, memory card) I put it all back together and now my memory card is not working! I have taken it out and cleaned it so many times... over the past few days. I just cant seem to get it to work... HELP!!