ubuntu eth0 not reconnecting after cable unplugged

Question

I'm running kubuntu 9.10 w/ gnome, I have a static IP defined in /etc/network/interfaces

When I unplugged my network cable and rebooted, then reconnected the network cable I was not able to connect. I tried using sudo ifup eth0, and then ifconfig and it seemed as though the IP address had been assigned and I was connected, but I wasn't. I then did ifdown eth0, and again ifup eth0. For some reason I'm not able to access the network. Furthermore, I also attempted to connect via wlan, and was able to connect to the wireless network, but cannot "see" the network. I can't transfer data or access the internet or anything on the network including the router.

How do I resolve this?

topsy@monolyth:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1c:25:1c:df:70  
          inet addr:192.168.1.145  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21c:25ff:fe1c:df70/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5720 errors:0 dropped:0 overruns:0 frame:0
          TX packets:565 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:378035 (378.0 KB)  TX bytes:46832 (46.8 KB)
          Memory:fe000000-fe020000 

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:4 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:240 (240.0 B)  TX bytes:240 (240.0 B)

By access the network I mean the local network as well as the internet.

topsy@monolyth:~$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=9.14 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=1.24 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=1.01 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=1.00 ms
[snip... all OK, icmp_seq from 5-30, time between 0.981-1.25ms]
^C
--- 192.168.1.1 ping statistics ---
30 packets transmitted, 30 received, 0% packet loss, time 29035ms
rtt min/avg/max/mdev = 0.971/1.300/9.140/1.458 ms

topsy@monolyth:~$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
link-local      *               255.255.0.0     U     1000   0        0 eth0
default         192.168.1.1     0.0.0.0         UG    100    0        0 eth0

root@monolyth:~# cat /etc/resolv.conf
# Generated by NetworkManager

Answer 1

Try this:

> sudo /etc/init.d/networking restart

If this does not help, check that the cable is "really" plugged - i.e. do the lights on the interface and on the switch/router are lit on.

Please, also, post as part of the question the output of these commands:

> ifconfig

> ping 192.168.1.1

> cat /etc/resolv.conf

> route