I've recently noticed how some players cannot take screenshots because the F2 on the computer being the bright option or something related. If you wanna take a screenshot anytime, you can follow the following steps:

1. Press Esc (If you're in a world)
2. Go to settings
3. Go to the controls section
4. Find the "Take screenshot" option
5. Change the F2 to any key you want to change it. You do that by pressing the previous button and press the key you want to change it to.

If you can't find the screenshot you take, go to the search bar:

and type "%appdata%" click on the roaming folder

-> .minecraft -> screenshots

And there you go.

I hope this guide helped :D