Corupt file on micro sd card

I have a Nextbase 402g dashcam with a Sandisk Ultra 32Gb card installed.
on the 24/02/16 I was a in car accident, and i cant find the file recording the journey when I had the accident.
Every journey I had before and after accident is there.
The dashcam as been sent back to nextbase but they were no help.
I await for any comments please

With my dashcam, (FalconZero) any file with an impact trigger goes to a protected folder on the SD card and has to be accessed by PC. YMMV. If the 12v power went off in the collision, anything can happen.

Something like ISOBuster might be able to recover a bad file.