Saving games stoped working (Zelda)

[machom]

Excuse my lack of knowledge. I’m almost completely unfamiliar with this.

I have a Raspberry Pi with RetroPie that I set up a few years ago. I don’t remember how I managed to do it, but I probably followed some guide somewhere.

I recently started playing on it again, and when I continued my saved game in Zelda: A Link to the Past, it seems like I can no longer save my progress. I defeated the boss in Dungeon 4 in the Dark World, paused, and selected “save and quit,” but when I started the game again later, I ended up back on the pyramid in the Dark World, and Dungeon 4 was incomplete.

I’ve searched and looked for information here on the site about what to do, but I don’t get it.

Could some kind soul walk me through the problem step by step, as if I were 5 years old?

I don’t know which version of RetroPie I have. I tried to find where it says that, but I couldn’t.

Thank you so much in advance for your help!