Both I'd say.
Try Start-->Run-->ncpa.cpl
Right click on your Network connection and select Enable (Note: may not be in list if it's already enabled)
Confirm your Network cable is secure, or replace it with a known good one
Does the Network icon actually show up in Network Connections?
If not, try:
Start-->Run-->devmgmt.msc
And confirm that you do not have any unknown or querried devices (yellow mark)
ie confirm you do have the correct drivers installed
Still not in Device Manager or Network Connections?
If not, try:
Restart your computer
Press the key (DEL or F2 or some other key?) to get into system bios (cmos or setup)
Locate your Network device, and confirm it's enabled
Failing all this
Please supply your computer make and model, Windows version
And if the network icon is visible, and what you have tried so far