Help me please

Hello! I really need your assistance right now. Since I changed my SD card, it looks like the system is broken down and I’m totally clueless what to do or fix. Can someone show me a direction, please? I’d really appreciate your help!

You could put in your old card, make a backup to a USB device with dietpi-backup, then install DietPi on your new card again and restore your system fron the backup, again with the use of dietpi-backup.

What exactly did you do and what do you mean, your system is messed up?

yes, some more explanation would be needed what exactly your issue is.