1 METHOD 1: UNINSTALL AND REINSTALL.
This pretty much explains itself but what you need to do is as follows:
Open the 'Control Panel' on your pc.
You will find 'Programs' on the bottom left and it says 'uninstall a program'
Once you open 'Programs', search for a) Apple Application support (32 bit) b) Apple Application support (64 bit) and c) iTunes.
Uninstall these one by one.
Now restart your computer.
Once it is switched back on, download iTunes and it will now recognize your iPhone.
2 METHOD 2: BONJOUR APPLICATION
Not many of you may know this but iTunes needs the Bonjour application to function properly. Oxygen for us, Bonjour for iTunes! Following are the steps to ensure the iPhone and iTunes connection:
Right click on 'Computer'.
Go to 'Manage'.
Now you will see 'Services and Applications' as the last option, click on it.
Double click on 'Services' and select the 'standard' tab.
Once you're here, check whether the 'Apple mobile device service' and 'Bonjour application' are working well.
To check this, right click on it and go to properties.
Ensure that the 'startup type' is 'automatic'.
Once done, click 'apply', 'start' and finally 'okay'.
Now repeat the same with 'Bonjour'.
3 METHOD 3: DEVICE MANAGER
Computer>right click>manage>device manager>portable devices>right click>Apple>update>driver software>browse computer
What this method does is it updates the iTunes on your pc to the latest available version. This works for the 64 bit. However, if you use the 32-bit version, don't worry. Just look for Program function x86. The size of this download is 2.34 GB.
4 METHOD 4:
Start by opening iTunes. Click on the 'iTunes' tab. Click on preferences. Then go to 'suitable preferences'. Open 'parental controls'. You will find 'access', click on 'allow access'. Hopefully, your iTunes should connect now.
5 METHOD 5: EJECTED?
You may see a tab on the top right corner on iTunes that displays the name of your iPhone if it is connected and there is a triangle symbol under it. If you accidentally might have clicked on it there is a chance that even when the USB is connected to both devices, ie your pc and your iPhone it may not recognize it. Check this once and you're almost done!