@bollwerk mame2010 isn't really recommended, but you could look at the mame2003 docs to show how you would revert to default controls: https://retropie.org.uk/docs/lr-mame2003/#mame-menu
if you hunt around your rom and BIOS directories, you may find the same default.cfg for mame2010. i'm not sure where it will be. if that deleting that doesn't fix the issue, then maybe mame2010 doesn't have good default controls here - a keyboard might work?