Hi Shen Tan
Is your only way of contacting your gf by the internet? Can`t you phone her or write to her? (Does she have your home address or phone number?)
If you can`t, and she`s not replying to your mails, what could be the problem? Perhaps she`s ill or someone in her family is ill. She may be very busy. Perhaps she can`t access a computer at present. Or she might be unsure of her relationship with you and is thinking things over. Sorry to say that but it is a possibility.
The problem with internet-only friendships is that it`s so easy to break off from the other person. Don`t give up hope just yet