There's something in recent years that I've noticed as a fiction writer, and it's that sometimes, you just don't feel connected to your characters anymore. Whether it's a huge gap from the last time you worked on it or the characters were made so long ago that you just can't imagine what they like anymore, what they'd want to be when they grow up, etc. Its frustrating. One of the books I'd been working on for ages hasn't really turned out like I've wanted because I started the book so long ago that the characters seem almost foreign to me now. They're still in high school, they're naive, and overall just harder to relate to now that I'm in my second half of college.
Feeling disconnected from your characters in a fiction piece you're writing doesn't mean you're a bad writer. I've had to come to terms with that recently. It doesn't mean you suck, it just means that maybe it's time to work on something else. Maybe these characters weren't the ones you were supposed to stay attached to, you know? The characters I write (and I'm sure the ones you all write, too) I feel connected with as if they're actual people. I'll see things in stores and say oh hey, that looks like something *insert OC name here* would wear/ buy. It can be really exciting, especially when it's a character I really feel close to, but sometimes all of that just has a way of disappearing, leaving you feel like you did something wrong in your writing process.
Well, things I've tried to become closer or reconnect with characters have sometimes worked, sometimes not, but it never hurts to give it a try. You could list things they like, list their physical traits if you're a little hazy on their specific details. List what music they listen to, who they look up to, who they aspire to be. A thing I started doing recently was using Pinterest to make Original Character boards and filling them with things with an aesthetic close to what the character would enjoy. It's really helpful, and also really fun, especially if you love Pinterest like I do. You could dedicate a page in your scrapbook to them, or write a little paragraph but get in their head and say what you think your character would say.
Becoming reconnected with characters can be really exhausting. Sometimes you'll feel like there's just no way of getting them back, but hey, if you made them, they've gotta be in there somewhere, right? And even if they aren't, who says you can't grow apart from characters, too? If you can grow away from old friends and music you used to like, doesn't it make sense to be able to grow apart from your characters you once loved? So don't beat yourself up about it. I wish you all luck reconnecting with your OC's. Write on!