My MS Pro Duo has started playing up. It is a Sony 4GB and I used it for homebrew / multimedia on my PSP. One day, I put it in my brother's Sony Ericsson W810i. The phone did not load with the card in, and when put in the computer or PSP it would say there were no files on it but that space was being taken up. Would anyone be able to help me?

put it into your computer, right click, and click "Format"

It will erase everything, but it should work again.

Or you could also put it in the PSP and go to System Settings and Format it there.

I knew that, but is there any way of retrieving my data e.g. - Save Data, Music, Homebrew and Videos? Oh, by the way, it only started playing up since I put it in the W810i.

I just found out that my PSP-1001 will soon be fixed. Yay! I recently bought a brand-new PSP-3003, but a little while ago I bought a broken PSP-1001, which was bricked and the screen was damaged.