Why is my Audi Q7 keyless entry not working?

Since Your keyless entry for Your AudiQ7 was presumably working before, I'm going to assume that this isn't an issue where Your keys haven't been progRammed correctly. Thus, the typical reason for Your key FOB to suddenly stop working is that the battery inside it has become discharged to the point that it's basically dead. You'll want a CR2032 ("watch battery") to fix it up; they're only around $3-$5, and You can snag one at Wally World or the like. More complicated issues with the FOB would be if the internal PCB has become cracked through use; don't feel bad, I've got gorilla hands, too - it happens. But it's most likely it's just the battery.