Computer LAN Card 找不到

My home computer recently goes crazy. I was surfing the internet one day and it suddenly told me it could not local my 網卡﹗So I could not access the internet for days. I try many ways but my motherboard just could not recognize my LAN card. I am quite certain my motherboard 有問題﹗It is barely 3 years! So I guess it is time to 破財消災﹗