First try a ifconfig to check wether you are connected or not and what are the names of he interfaces.

if resolv.conf is not there create it manually and add : nameserver 208.67.222.222

try changing the hosts file like that:

127.0.0.1 localhost loopback
::1 localhost

hosts is configured in this way:
ipaddr hostname series of aliases

try a "dmesg|grep eth" to check wether the driver is loaded or not.
then lsmod to see if the module is loaded.

what ethernet manager are you using?
if you don't know try to connect manually, without dhcpcd
ip addr add <IP address>/<subnet mask> dev <interface>
ip route add default via <default gateway IP address>

remember that you need to know the subnet mask of the router to put the /<subnet mask>
This is simply done by doing, for example if the subnet is 255.255.192.0
255=1111 1111 ; 8x1
255=1111 1111 ; 8x1
192=1100 0000; 2;1
0 = 0000 0000; 0x1
sum = 8x2 + 2 = 18
so here 255.255.192.0 is equal to /18
subnet is really important to connect to the gateway because otherwise you'll not be considered on the same network.