I found solution in http://www.zyxware.com/articles/2680/solved-wired-connection-eth0-not-detected-in-ubuntu-12-04

I downloaded compact-wireless-2012-07-03-p.tar.bz2

Here the steps i followed along with output

1. shravankumar@shravankumar-Lenovo-G580:~/Desktop/compat-wireless-2012-07-03-p$ scripts/driver-select alx

Output:
Processing new driver-select request...
Backup exists: Makefile.bk
Backup exists: Makefile.bk
Backup exists: drivers/net/ethernet/broadcom/Makefile.bk
Backup exists: drivers/net/ethernet/atheros/Makefile.bk
Backup exists: Makefile.bk
Backup exists: Makefile.bk
Backup exists: drivers/net/ethernet/broadcom/Makefile.bk

2.shravankumar@shravankumar-Lenovo-G580:~/Desktop/compat-wireless-2012-07-03-p$ make

output:
make -C /lib/modules/3.2.0-23-generic/build M=/home/shravankumar/Desktop/compat-wireless-2012-07-03-p modules
make[1]: Entering directory `/usr/src/linux-headers-3.2.0-23-generic'
scripts/Makefile.build:44: /home/shravankumar/Desktop/compat-wireless-2012-07-03-p/drivers/net/ethernet/atheros/alx/Makefile: No such file or directory
make[4]: *** No rule to make target `/home/shravankumar/Desktop/compat-wireless-2012-07-03-p/drivers/net/ethernet/atheros/alx/Makefile'. Stop.
make[3]: *** [/home/shravankumar/Desktop/compat-wireless-2012-07-03-p/drivers/net/ethernet/atheros/alx] Error 2
make[2]: *** [/home/shravankumar/Desktop/compat-wireless-2012-07-03-p/drivers/net/ethernet/atheros] Error 2
make[1]: *** [_module_/home/shravankumar/Desktop/compat-wireless-2012-07-03-p] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-3.2.0-23-generic'
make: *** [modules] Error 2

3. hravankumar@shravankumar-Lenovo-G580:~/Desktop/compat-wireless-2012-07-03-p$ make install

output:
FATAL: Could not open /lib/modules/3.2.0-23-generic/modules.dep.temp for writing: Permission denied
make: *** [uninstall] Error 1

4. shravankumar@shravankumar-Lenovo-G580:~/Desktop/compat-wireless-2012-07-03-p$ modeprobe alx

output:
No command 'modeprobe' found, did you mean:
Command 'modprobe' from package 'module-init-tools' (main)
modeprobe: command not found

I am new to Ubuntu ,Please help me.

Thanks in advance