recorded forty minutes of video and clicked on end recording. then I went to check the quality of the recording and saw that this video was saved with a size of 4 kilobytes. I thought that if I fix it through the built-in fixer, then something will be fixed. But in the end, nothing has changed anyway. this video starts but lasts 0 seconds. who knows what to do, please help.)

Hello voldemar198_FX,

We are afraid that we don't have any solution for the broken file if BandiFix didn't work for it.

Please refer to the following FAQ page and record again with the latest version of Bandicam.
https://www.bandicam.com/faqs/cannot-run/

Thank you.