Urgent help needed in opening files

I am making banners on Photoshop as part of an assignment. I spent countless hours on many of them. About two hours back I tried opening some of my banners only to see the "It is not a valid Photoshop document." I know this issue has been discussed numerous times, but none of the solutions work. Not a single Photoshop repair tool or any other tool has worked, as the all cannot recognize the file. The banners do not open on any other software either such as photo viewer or paint. The simple solutions such as change file extension t .psd don't seem to work either.

This applies to about four of my posters, which I guess were open when my laptop completely shut off. The rest of the banners open perfectly fine

Is there anything I can do? This is quite urgent as mentioned previously