Ok, when you say you can upload sketches I assume you mean through the USB, correct?
If so, upload the YunSerialTerminal sketch, it is under File->Examples->Bridge->YunSerialTerminal.
Then open the serial monitor, Tools->Serial Monitor
In the box at the top (to the left of the send button) type -
cat /etc/config/wireless |grep disabledand click the send button.
Do you see this?
option disabled '0'If so, continue with the below, if you see this
option disabled '1' ignore the instructions/questions below they won't work until we get the wifi enabled.
In the box at the top type
ifconfigand click the send button.
You should see something like this in the output:
wlan0 Link encap:Ethernet HWaddr 90:A2:DA:F1:04:27
inet addr:192.168.2.203 Bcast:192.168.2.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:7192 errors:0 dropped:1825 overruns:0 frame:0
TX packets:560 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:1224833 (1.1 MiB) TX bytes:92250 (90.0 KiB)
Type the address by inet addr: in your web browser (192.168.2.203 in the example above, yours will most likely be different)
Do you get the Yun login page?
avahi-browse -a & in the box at the top and click send. You should see output that includes two lines like these:
+ wlan0 IPv4 yunName _arduino._tcp local
+ wlan0 IPv4 Secure Shell on yunName _ssh._tcp local
What do you see in the output where yunName appears in the example above?