Save problem WWF No Mercy ROM

Hi guys. My game won't save anymore. This sucks because I really enjoyed playing it. Is there anything I can do? When I save it it also makes a cracking noise and stuff. I'd really love to make it save progress again and keep my created characters and stuff. Any help?

EDIT: In more detail: I can save it, it autosaves, but when I go back to the main menu, then back to what I saved, it's back to how it was before I changed it. So I can play but it's stuck in 1 save state the whole time. I don't know what to do to make it remember what I change.

But it's the only game that won't save, how do I know it's not the rom. And how do I give it writing permissions? Like I said, it USED to save so it seems to me it's just broken.. But I'd like to know how to fix it.

I really don't know what to do anymore, I just deleted the rom, re-downloaded it, and it still has the same cracking noise when I save and it doesn't actually save. Wtf. If the save file is broken, is there a way I can repair it? Please help..