software library tells me internet connection is unavailable

I am on 11.10

Do you use a proxy server? How are you connected to the internet. Do you use other services other than http? Are you behind a corporate system, which may have its own firewall?

Can you open a terminal, run these commands and post the results back here?

echo $HTTP_PROXY
ping -c 4 www.ubuntu.com
sudo /sbin/ifconfig -a
lshw -C network

I don't use any proxy, but it's strange because 4 days ago there was no problem, and 3 days ago it told me that, i thought it was a small bug so i waited, but i've still the problem that's why i was asking.
I'm connected by wifi, connection is ok

for the result of the commands :

PING www.ubuntu.com (91.189.90.41) 56(84) bytes of data.

--- www.ubuntu.com ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3023ms

pierre@pierre:~$ sudo /sbin/ifconfig -a

[sudo] password for pierre:
eth0 Link encap:Ethernet HWaddr d0:67:e5:31:f4:76
          UP BROADCAST MULTICAST MTU:1500 Metric:1
          Packets reçus:0 erreurs:0 :0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:1000
          Octets reçus:0 (0.0 B) Octets transmis:0 (0.0 B)
          Interruption:18

lo Link encap:Boucle locale
          inet adr:127.0.0.1 Masque:255.0.0.0
          adr inet6: ::1/128 Scope:Hôte
          UP LOOPBACK RUNNING MTU:16436 Metric:1
          Packets reçus:920 erreurs:0 :0 overruns:0 frame:0
          TX packets:920 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:0
          Octets reçus:138834 (138.8 KB) Octets transmis:138834 (138.8 KB)

wlan0 Link encap:Ethernet HWaddr a0:88:b4:88:23:e4
          inet adr:192.168.2.14 Bcast:192.168.2.255 Masque:255.255.255.0
          adr inet6: fe80::a288:b4ff:fe88:23e4/64 Scope:Lien
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          Packets reçus:433819 erreurs:0 :0 overruns:0 frame:0
          TX packets:343408 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:1000
          Octets reçus:611313959 (611.3 MB) Octets transmis:38062481 (38.0 MB)

Your connection does not appear to be OK -- you have 100% packet loss -- no ping packets are getting through to the internet and back. This means something is odd with your network -- either the connection is broken, or ping packets are being dropped, which would imply that your network is in part filtered.

You do have an internal address, it appears through. Also DNS resolution appears OK. Odd -- though could be cached.

How do you know the connection is OK -- can you use an internet browser normally? Do other computers run on your network? Are they OK ? Can you connect to your router with a cable and then use the internet successfully?

Can you log onto your router successfully -- does it report that the internet is functional (often home routers have a test functionality for this.)?

Can you run:

sudo /sbin/route -n
ping -c 4 192.168.2.1

And also see if opening a browser and navigating to
http://192.168.2.1/

brings up anything.

I just changed the downloading source, and it seems to be functioning now...

Thanks for your help

Problem seems to be solved