ipod with wlan settings doesn't get wifi

My son bought an ipod touch 32gb from his mate. He conected it to our home wifi ( i didnt see him doing it) and used it for a few days. He then connected to a friends pc and put some music on it. Since then we haven't been able to connect to our wifi again.. It only gives us an option for WLAN rather than wifi, however from what i understand we should still be able to get onto wifi. Any ideas??