Recover Videos - USB Mistake

Hello,

2 months ago, I synched 77 cherished videos of memories from my Photos app to my USB stick and waited until they were completely uploaded onto it. But today, I wanted to revisit a certain video and to my surprise, all the videos have turned into jpeg which now just shows me the first shot of the video but it is only saved as a picture... Is there still a way to recover these videos as I don't have any other way to get to them.

Please help me as soon as possible!

Thank you