I am saying that pushing Windows Key (or WinKey, if you prefer) plus the PrtSc (or Print Screen) key at the same time will cause Windows 10 to take a full screen screen shot and place the resulting file in your Pictures library, in a folder named Screenshots. When it does this you get a very brief "gray veil" go over the screen, but since the audience here is, for the most part, unlikely to be able to benefit from that visual cue I didn't bother to mention it. The individual screenshot files will be in PNG format and will have the names Screenshot(N), where the N will start out at 1 and keep on going as you take screenshots. Even if you delete what you had, it appears that Windows 10 itself remembers whatever the count was, as I just took a screenshot using the above noted technique and it was named Screenshot(6).png in my Screenshots folder even though there were no other items there.
If you want a windowed screen shot, rather than a full screen screen shot, use WinKey + Alt + PrtSc. Prior to Windows 10 Version 1809, this would cause the resulting screenshot of the window with focus to be placed in the Videos library, Captures folder, with a name based on the window being captured with the current date-time stamp behind that, still in PNG format. Oddly enough, windowed screen shots are taken via a convoluted method that employs Xbox that comes with Windows 10, don't ask me why. Now, after installing Version 1809, and I did it in the first week it was available, when I tried to take a windowed screen shot I would eventually get a pop-up menu telling me that I needed to enable game play on the computer to allow this to occur. All I did was check that checkbox, dismiss the dialog, and everything went back to working as I described prior to the Version 1809 upgrade. These windowed screen shots take a few moments to be taken and you will get a notification (formerly known as a toast) sliding out when it is complete and sitting in the Captures folder.
Brian - Windows 10 Home, 64-Bit, Version 1809, Build 17763
Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.
~ H.L. Mencken, AKA The Sage of Baltimore