ifup returns an unknown interface error

I'm still learning Linux and I'm less familiar with Ubuntu. I have a Ubuntu image that I'm using in VirtualBox on a windows machine. It was able to connect and get an IP address up until about a week ago. I made no configuration changes. I've tried placing VirtualBox settings to use NAT and also tried bridged, it didn't seem to make a difference. If I run ifconfig, it gives me enp0s3, but if I run ifup enp0s3 I get an unknown interface enp0s3 error.

uname -a output:

Linux cs165-VirtualBox 4.10.0-40-generic #44-16.04.1-Ubuntu SMP Thu Nov 9 15:33:07 UTC 2017 i686 i686 i686 GNU/Linux

ifconfig output:

enp0s3    Link encap:Ethernet  HWaddr 08:00:27:eb:53:a4
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:720 (720.0 B)  TX bytes:240 (240.0 B)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:4 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:240 (240.0 B)  TX bytes:240 (240.0 B)

What I get when I try to restart the network service:

~> /etc/init.d/networking restart
[ ok ] Restarting networking (via systemctl): networking.service.

ifup returns an unknown interface error:

~> ifup enp0s3
Unknown interface enp0s3

Try using

sudo ifconfig enp0s3 up

or

sudo ifconfig enp0s3 down 

or

sudo ip link set dev enp0s3 up

or

sudo ip link set dev enp0s3 down

Hope this helps!