Unable to connect to wireless networks

Hello! I have a Dell Inspiron 13 5379 2-in-1 with Windows 10, around 1 year and 7 months old.

I installed a Windows update (it might be a coincidence though, since going back to an earlier update doesn't solve the problem) and then suddenly, my laptop's unable to connect to Wi-Fi. The network troubleshooter doesn't detect any problems.

To elaborate, the Network & Internet Settings have stopped showing a WiFi section:

Selecting "Change adapter options" would only show Bluetooth Network Connection 2 and Ethernet.

Trying to "set up a connection or network" would show this (note the lack of wireless options): 

Device Manager shows this (the Microsoft Wi-Fi Direct Virtual Adapters are both "not connected to the computer. (Code 45)") 

I have tried reinstalling the WiFi driver that is shown in the Dell Support (Qualcomm QCA61x4A/QCA9377 WiFi and Bluetooth Driver ) but it keeps saying that it cannot be installed whenever I try to install it.

Pressing Fn+PrtScr (the button with the internet sign) only turns on/off the Airplane Mode.

Many, many thanks for those who can help me!