As a first-time mom, I try everything to cheer up my kid if he ever has a bad day. But somehow I feel lost.. I need tips on how to talk to my child after a bad day at school.
First of all, the fact that you even asked this question means you are already doing better than half the parents out there 
When my kid comes home looking like someone cancelled Christmas, the worst thing I ever did was immediately ask what happened? That question goes nowhere. They shut down completely.
What actually worked for me was just… being quiet. Sit nearby. Offer a snack. Let them decompress for like 20 minutes before anything. Kids process stuff at their own pace, and sometimes they just need to know you are around without being interrogated about their day.
Then when they do start talking, just listen. Don’t jump in with solutions straight away. Don’t say oh that’s nothing, when I was your age… just listen. That’s honestly 90% of it. 
Okay real talk, I used to try so hard to fix my son’s bad days that I made them worse 
Like I’d come in with activities, snacks, a whole plan, basically a PowerPoint presentation on why tomorrow would be better. And he would just look at me like I had completely lost it.
Kids don’t want their problems fixed in the first five minutes. They want to feel like their problems make sense. There’s a big difference.
@ShredRed said it right, the snack and silence combo is underrated. I’d add one thing though if they do open up, don’t immediately try to solve whatever they are describing. Ask more questions instead. And then what happened? is a magic phrase. It keeps them talking without making them feel like they are being coached. 
I raised three kids and watched plenty of parents overthink this exact thing.
The simplest advice I can give: don’t make a big production of it. If your kid had a rough day and you come running with big worried eyes and a thousand questions, they feel like something is really wrong, even if it wasn’t that serious.
Normal voice. Normal routine. How was your day if you want, but don’t dig if they say fine. Let them come to you. And when they do, sit down properly. Not while cooking. Not while looking at your phone. Actually sit with them.
Kids remember that their parent stopped everything to listen. That’s the part that sticks. Not the advice you gave. Just that you were there. 
Oh I feel this post so much because I went through the exact same thing recently and had no idea what I was doing either 
My daughter came home one day barely talking, went straight to her room. I was panicking inside but trying to look calm on the outside. Eventually I just knocked on her door and said something like I’m here if you want company, no pressure. And then I left.
Twenty minutes later she came out and we talked for an hour.
I think the thing I didn’t get at first is that kids need to feel like talking is their idea, not yours. The moment they feel like you are pushing for information, they go quiet. But if you make it easy and low pressure, they usually come around. At least that’s what worked for me! 
Something that helped me shift my whole approach was this: I stopped trying to make my kid feel better and started just trying to make them feel understood. Those are really different goals. Trying to fix someone’s mood is exhausting for both of you. But just sitting with them in whatever they are feeling that’s actually manageable.
So when my son has a rough day, I don’t say don’t worry, it’ll be okay. I say something like that sounds really frustrating. Full stop. No silver lining attached. And then I wait. Nine times out of ten, he keeps talking. Because he feels like I actually got it, instead of trying to talk him out of his feelings. @BoomerRing above is right that sitting down properly matters too, the physical act of stopping and being present says more than any words. 
My personal rock bottom in this area was when my kid had a bad day, I asked what happened, he said nothing, and I then proceeded to list every possible thing it could have been for the next ten minutes like some kind of detective
Was it something with a friend? A teacher? Did something happen at lunch? Was it PE?
He looked at me and just said dad can you stop…
And that was the moment I understood. You cannot extract feelings from a child like you are defusing a bomb. You just have to create the conditions where talking feels safe and then back off.
Now I just say rough day? and nod. If he wants to go further, great. If not, we watch TV and have dinner and half the time he brings it up himself later. Way less stressful for everyone involved.
@SyntaxSmith, I think you are being way too hard on yourself. Feeling lost about this doesn’t mean you’re failing, it just means you care, which is the starting point for all of it.
A few things that genuinely helped me:
Don’t talk in the car ride home if you pick them up. That quiet time is actually really good for both of you. Let them decompress before anything else.
When they do start sharing something, reflect it back. If they say nobody played with me today, don’t say I’m sure they didn’t mean it. Say that must have felt really lonely. Kids need to feel like their version of events makes sense before they can move on from it.
And honestly, the days where you don’t crack the code at all, where they go quiet and nothing clicks, those happen to every parent. It doesn’t mean you did something wrong. 
Something nobody really talks about, you don’t always have to talk.
I started doing this thing with my daughter where if she was having a rough day, we’d just draw or colour something together. No agenda. No conversation required. And somewhere in the middle of that, she’d just start telling me stuff.
There’s something about doing a quiet activity side by side that lowers the pressure completely. You are not face to face, which for some kids is less intense. You arw just two people doing something, and conversation happens naturally.
@MicroLauncher’s point about creating conditions instead of extracting information is exactly it. An activity is just another way of doing that. Not every kid is a talker, and that’s fine. Find the thing that opens the door for your kid specifically, it might not be a conversation at all at first. 
The advice in this thread is solid. I’ll just add the one thing I kept getting wrong early on.
I used to validate my kid’s feelings and then immediately pivot to so here’s what you should do next time. And I thought that was good parenting. Acknowledge the feeling, then solve the problem. Makes sense, right?
Nope.
The moment you shift to advice, they switch off. Because now it feels like a lesson instead of a conversation. They weren’t asking for a solution. They wanted to be heard.
So now I sit with the feeling part way longer than feels comfortable. Like almost uncomfortably long. And only if they ask what do you think I should do? do I offer anything. Otherwise I just stay in the listening lane. Took me a while to get there but it changed everything. 
Reading through all of this and the common thread is really clear, listening is the actual skill here, not fixing
One thing I’ll add from my own experience: sometimes my son just needs to be physically close to me. Not talking. Just sitting on the couch watching something dumb together. And that counts. That’s still connection.
You asked how to talk to your kid after a bad day, @SyntaxSmith. Sometimes the answer is, you don’t have to say much at all. Just show up. Be nearby. Make it easy to talk when they are ready. That’s the whole thing.