Hello, you can't recover deleted the files on the SD card with your iPad.
You'll need to use a PC or Mac with an appropriate data recovery utility, to recover the deleted files on your dash cam.
(1)If you have a MacBook. Try iBoysoft Data Recovery for Mac, which helps you recover all files on the SD card quickly and deeply.
(2)If you have a PC, you can utilize iBoysoft Data Recovery, a effective recovery tool to get back deleted files.
Hope you can find the files at last.
Also read: How to Recover Deleted Files on SD Card (Windows/Mac)