network icon is missing

If you connect the wired connection and run:

sudo dhclient3 eth0

You will get a network address. Just because there is no notification, doesn't mean it doesn't happen.Wired connections will automagically ask for an address once connected but you want to see it happen so the command I gave will show you it occurring.

If you press ALT+F2 and run;

nm-applet

Does the item not reappear?

No. It was not appear. When I execute 'nm-applet' it is showing a error message stating that 'file:///home/balu/nm-applet'

Hmm, ok does the dhclient3 command work, you never said....

Yes it is working properly I think. There is a lot of text I'm just typing the part of it.

Internet Systems Consortium DHCP Client v3.13
Copyright 2004-2009 ///
All right reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:26:22:a6:35:c5
Sending on LPF/eth0/00:26:22:a6:35:c5
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3
.
.
.
No DHCPOFFERS received.
No working release leases in persistant database - sleeping.

I cannot access even "Wired" or "Wireless". Should I have to reinstall all the packages relevant to that. If so... How I have to do that? Please let me know if there is an answer for this?

I cannot access even "Wired" or "Wireless". Should I have to reinstall all the packages relevant to that. If so... How I have to do that? Please let me know if there is an answer for this?

I cannot access even "Wired" or "Wireless". Should I have to reinstall all the packages relevant to that. If so... How I have to do that? Please let me know if there is an answer for this?

I cannot access even "Wired" or "Wireless". Should I have to reinstall all the packages relevant to that. If so... How I have to do that? Please let me know if there is an answer for this?

ok

can you give the output of:

sudo lshw -C network

Thanks

Sure... It is as below.

*-network
    description: Network controller

Sure... It is as below.

*-network
    description: Network controller
    product: BCM4312 802.11b/g LP-PHY
    vendor: Broadcom Corporation
    physical id: 0
    bus info: pci@0000:02:00.0
    version: 01
    width: 64bits
    clock: 33MHz
     capabilities: pm msi pciexpress bus_master cap_list
    configuration: driver=b43-pci-bridge latency=0
    resources: irq:18 memory:d8500000-d8503fff
*-network DISABLED
    description: Ethernet Interface
    product: RT8101E/RTL8102E PCI Express Fast Ethernet Controller
    vendor: Realtek Semiconductor Co., Ltd.
    physical id: 0
   bus info: pci@0000:03:00.0
   logical name: eth0
   version: 02
    serial: 00:26:22:a6:35:c5
   size: 10MB/s
   capacity: 100MB/s
   width: 64bits
    clock: 33mhz
 capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet phsical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
   configuration: autonegotiation=off broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half latency = 0 link=yes port= MII speed=100mb

I reinstalled network manager gnome. now it is fine. thank you all