[CentOS] Network manager cannot connet to the Internet

Sat Sep 3 10:08:26 UTC 2016
sunyeping <sunyeping at aliyun.com>

Dear all,
I find out of a sudden my Network manager cannot connect to the Internet. My OS is Centos 6.7, and the version of Network manager is Applet 0.8.1. When clinking the  Network manager icon at the upper right conner at the Desktop of my compuer, I can see in the pop-up manu that there are two network  cards (Intel 82573E Gigabit Ethernet Controller (Copper) and Intel 82573L Gigabit Ethernet Controller) but only one link (System eth1) available. Usually when clicking the "System eth1" the Internet connection would be established. However from this morning clicking the "System eth1" only gives connect failure information. I don't know whether this is caused by intalling a large software package (ambertool 16 ) which requires many updates in my system yesterday.    But when I give "ifconfig" command in a gnome terminal, the output information seems to be correct:

[sunyp at localhost Desktop]$ ifconfig   
eth0      Link encap:Ethernet  HWaddr 00:25:90:72:E2:86  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:16 Memory:faee0000-faf00000 

eth1      Link encap:Ethernet  HWaddr 00:25:90:72:E2:87  
          inet6 addr: fe80::225:90ff:fe72:e287/64 Scope:Link
          RX packets:49 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:16386 (16.0 KiB)  TX bytes:3038 (2.9 KiB)
          Interrupt:17 Memory:fafe0000-fb000000 

lo        Link encap:Local Loopback  
          inet addr:  Mask:
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:90 errors:0 dropped:0 overruns:0 frame:0
          TX packets:90 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:6737 (6.5 KiB)  TX bytes:6737 (6.5 KiB)

What I can do now? Could anyone help me with this problem?
Best regards.
Yeping Sun