Wired connection not working Ubuntu 12.04

My connection was fine until now, but my wired connection is not working in Ubuntu 12.04. I have installed Ubuntu 12.04 along side Windows 7 partition and the connection works on Windows but not on Ubuntu 12.04. I have no problem with wireless connection as well. The problem is specific to the wired connection on Ubuntu 12.04. I have included a few details below.

ifconfig

eth0      Link encap:Ethernet  HWaddr 00:1e:ec:8d:f0:03  
          inet6 addr: fe80::21e:ecff:fe8d:f003/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1 errors:0 dropped:0 overruns:0 frame:0
          TX packets:376 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:316 (316.0 B)  TX bytes:33769 (33.7 KB)
          Interrupt:19 

eth2      Link encap:Ethernet  HWaddr 00:21:00:4e:ac:58  
          inet6 addr: fe80::221:ff:fe4e:ac58/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:1660 errors:0 dropped:0 overruns:0 frame:28
          TX packets:1846 errors:61 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1372676 (1.3 MB)  TX bytes:254576 (254.5 KB)
          Interrupt:18 

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:16436  Metric:1
          RX packets:1862 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1862 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:155767 (155.7 KB)  TX bytes:155767 (155.7 KB)

sudo lshw -C network 

 *-network               
       description: Wireless interface
       product: BCM4312 802.11b/g LP-PHY
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: eth2
       version: 01
       serial: 00:21:00:4e:ac:58
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=wl0 driverversion=5.100.82.38 ip=10.0.0.3 latency=0 multicast=yes wireless=IEEE 802.11bg
       resources: irq:18 memory:99700000-99703fff


 *-network
       description: Ethernet interface
       product: RTL8101E/RTL8102E PCI Express Fast Ethernet controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:04:00.0
       logical name: eth0
       version: 02
       serial: 00:1e:ec:8d:f0:03
       size: 100Mbit/s
       capacity: 100Mbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=N/A latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
       resources: irq:19 ioport:3000(size=256) memory:93410000-93410fff memory:93400000-9340ffff memory:93420000-9343ffff

Solution 1:

I encountered the same problem after upgrading to 12.04.

The following solution worked for me:

1. Open this file in a text editor as root:

   gksu gedit /etc/network/interfaces
   

2. Add these lines to the file:

   auto eth0
   iface eth0 inet dhcp
   

3. Save the file and quit the text editor.

4. Now restart the network:

   • How to restart the networking service?

Solution 2:

All I had to do was unplug the ethernet cable from the port and plug it again. It worked. Ridiculous.

Solution 3:

Try to enable / disable the connections, also remove the currently active and add it another time!