What is this file type?

[MahaB82A]

This is not a *.JPG file but it shows just JPG. What is this file type? 

[Peru Bob]

If it doesn't open in Photoshop, try opening it in IrfanView and resave it.

https://www.irfanview.com/

[D Fosse · Accepted solution]

Since there's no period, it technically doesn't have an extension.  Windows reads backwards and whatever is after the last period is the extension.

Just rename the file, with extension.

(all this assuming you have extensions visible in Windows. If not, turn it on).

[MahaB82A]

Thanks for the help.

[Stephen Marsh]

I once created an ExifTool command to fix such issues:

https://prepression.blogspot.com/2017/09/exiftool-automatically-adding-missing.html?q=extension

[MahaB82A]

I downloaded this file to use. But it came without extension.

Pattern File

[Stephen Marsh]

So try adding .png or .jpg or .gif and see if it is then recognised.