I lost all my saves and gallery but my saves are still in my folder

I play the sims casually and have 1400 hours in it. I recently bought the 2 new kids the Glam essentials kit and the mudroom kit. When I went to open my game it acted like I had just opened the sims for the first time and all of my saves and families and houses were gone from my gallery. The strange thing is was when I looked at my documents and the save file folder all my saves were still in there, it’s like the game doesn’t recognize them or something even though I haven’t touched it. I don’t use Mods or CC so I have no idea how this could had happened. I’m not very tech savvy so I literally don’t know what to do about this and I’m freaking out