why are my iMessage bubbles green even though i’m texting someone with an iphone?

so basically how this all happened is when i was helping out my dad. My dad has a Samsung and i have an iphone. Something was going on with my dads phone so he swapped our sim cards just to try something hoping it would fix his phone, i won’t get into details. Anyways though. It wasn’t working so he put my sim card back into my phone and since then my imessages have been green. I’ve searched up ways to fix it and it worked but something isn’t working. When i go to settings and messages then turn on imessage, it doesn’t connect my phone number. The loading thing just stays there, i’ve been waiting for ages. I’ve tried restating my phone, re opening the app and it just wont work. And i am afraid to reset my network settings incase something happens or it doesn’t work.