Internet!

My workstation with Win98 is not browsing through Internet and not establishing any connection with the Internet. It is on LAN of an ISP and have all the correct settings it required to connect. In fact, it was very well couple of days ago but suddenly it start making this problem. It is browsing LAN very well and has no problem in it but not going on Internet. I have a router that work as a default gateway. Please help me out! If you want additional information do write me.
Thanks