networking – No Network Interfaces, unable to connect to internet

I installed Ubuntu on my desktop a week ago, and it’s been running fine all the time. Both wi-fi and ethernet were working even up to today. Then I rebooted my computer in the afternoon and suddenly there’s no internet. No network-manager applet in the menu bar, no Wireless in the settings, nothing but VPN in the Network settings, and there’s no more network interfaces other than lo.

I made a bootable usb, and was able to access both ethernet and wi-fi through the “Try out Ubuntu”, so I know it’s not my hardware.

I did a lot of searching around and haven’t found anything that works or is quite like the issue I have. How can I fix this?