Are you using a DSi or 3DS?
If you're using a 3DS, then follow this guide: https://gbatemp.net/threads/recover-ds-mode-after-an-nvram-brick-eg-after-using-a-ds-bricker.516444/
If you're using a 3DS, then follow this guide: https://gbatemp.net/threads/recover-ds-mode-after-an-nvram-brick-eg-after-using-a-ds-bricker.516444/
Try re-calibrating touch then.
If the issue persists, then try this guide for troubleshooting DS/DSi functionality: https://3ds.hacks.guide/troubleshooting#software-issues-on-devices-with-custom-firmware
Please join the Nintendo Homebrew server to see if they can help then:
https://discord.gg/C29hYvh
Because I'm out of ideas.
EDIT: One last idea. If the game is being run from the game card slot, make sure the Slot-1 touch mode setting is set to DS mode.
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