I have RCA by Thomson digital broadband cable modem it is DCM425 and i dont have a software for this driver can any one help for this

The trick about all this is that the software does not configure the computer, but the modem.
So once it has been configured through a computer then plugged to a router, any computer plugged to the said router will have access to the Internet.

The whole process of installing/configuring will happen if you replace the old modem and/or plug a new computer directly to the modem.

Plug the Ethernet cable into the yellow jack on the wireless router. Plug a wireless receiver (like Netgear or Belkin) into a USB port on the computer. The Belkin will come with instructions, software and a default password (on the bottom or the router). Install the CD drivers and follow the prompts.

That's just a MODEM it doesn't provide a wireless signal.

You can download drivers for the Thompson RCA DCM425 here

Download this PDF file - Thompson is same as RCA (?)

http://www.manualsonline.com/regman/exit/ct?url=aHR0cDovL3d3dy5tYW51YWxzb25saW5lLmNvbS9tZG93bmxvYWRzL2VjYTYzOTQxLTEwZTMtNDAwNC1hZDFkLTVmYmQ4YjJhMDhmYy5wZGY,&target=mexResource&idDeviceType=2719&idMfg=1572&idProduct=1901427&idThread=1197027&idMexResource=f28977

You may also find this site helpful.. http://www.simplehelp.net/2006/07/15/cable-modem-troubleshooting-rca-dcm425/

http://download.driverguide.com/driver/dcm425/Thomson/d1217065.html

http://members.driverguide.com/driver/detail.php?driverid=1217065

You can download the driver at either site and more

I wasn't been able to find your driver bu you may want to try this:
Driver Genius Professional 9.0.0.180

Check this thread:

http://www.digitalspy.co.uk/forums/showthread.php?t=555166

There is a website with the RCA425 USB modem drivers
http://helpdesk.powergate.ca/index.php?id=19

HERE is the manufacturer main link to download driver.

page also has manual on installing it and config modem properties.

 

http://www.thomson-broadband.co.uk/codepages/content3.asp?c=7&ProductID=511