Help please, I messed up the coding on the original default them on accident. Could anyone help me fix this?
Kindly Share you store url.
You Can rollback your Theme file where you have changed.
https://help.shopify.com/en/manual/online-store/themes/extend/theme-code#roll-back-to-an-older-version-of-your-theme
If you didn’t make a backup or duplicate, try and see if there are older versions you can restore
There’s also getting a fresh version of a theme an transplanting in unchanged code to the proper file.
If you need a professional to fix it contact me with store details for pricing. My email is in my forum signature.
How do I restart and find this default theme?
Do you mean the Published theme? follow the instructions in the link provided for the Published theme or the theme you were working on . Goodluck.