Wifi disactivated

Hello,
i have searched everywhere in the internet and i find this site very helpful. you see i bought my laptop asus last month. so far i am happy with my computer. yesterday i went out of town and connected my computer at other wifi networks. last night my wifi was still working. but when i woke up this morning my wifi is no longer activated. presently i am conneted through cable. i wanted my computer to be connected through wifi because it is easier for me when im moving around. i have tried pressing F2 and Fn at the same time in order to activate the wifi but to no avail. i am getting frustrated already. am i doing it right? is there something i should do first before i start pressing those keys? please, please help me!!! your help will be greatly appreciated! thank you so much ! hoping to get some solutions soon...