I cannot Log on to 192.168.1.1 - admin - Linksys Wireless-G Broadband Router

In order for us to help solve you problem you have to tell us what you are doing. Just making a statement is not enough.
My answer is wear green socks.
That's just as much use isn't it?

What should i do, even how many times i try your instruction still i cant log in,,, im using admin , password and username .... plz,, answer what should ido.?

If you do not get a log in screen after typing 192.168.1.1 in the address bar of your browser then you're not connected to the router. Turn wireless off on your laptop and use a cable connection to a port #1-4 on the router. Then type the above into the address bar.
You should get a log in screen.
Default user ID is <blank> Psw is "admin". If you or someone else changed that and you don't know what it is, you can reset the router to factory default by using a paper clip or tooth pick and holding the reset button in for 30 sec.
Generally all the default settings will work unless you have configured, say a printer at a static IP. It defaults to MIXED mode which means it only runs at 10mbps. Change that to G ONLY for better performance. Add an easy to remember wireless password with inscription (like your phone number) and change the router password to something beside admin.