Object doesn't appear in Final Render I just finished the Chair series by Blender Guru, but am obstructed with a problem.

In this picture you can clearly see the screws. This is Material Preview mode. 
In the picture above is the viewport Cycles render. You can clearly see that there is nothing abnormal about the screws.

As soon as I press F12 to do a final render I get this problem. I don't understand why the screws are not appearing. I made sure that the screws are not turned off for render. I tried going to something called View Layer, and I checking Single Render Layer.
I am some what new to Blender, if someone could explain it properly for a beginner that would be appreciated.
Select your chair back and check the Subdivision Surface modifier, you have not given the same subdivision level in viewport and render, so it won't bend the same when rendered. You rarely need subdivision as high as 4, bring it back to 2, like you've done for render, and move the screws a bit so that you can see them correctly, then render.