Can't drag and drop files to email

I was sending an email this week and needed to drag and drop a file. When I moved my screen over to click on the desktop and access my file, my Safari browser minimized and moved to the left side of my screen. I can click on my file, but when I drag it, it does not attach like before.

Is there a setting to restore to the prior mode? I could not find it if there is.

Thank you