Can not connect Laptop to any wireless modem

Hello,
My hcl laptop after changing the mother board could not connect to any of the wireless modem, neither at my office nor at my home. I am using the airtel broadband services.
I contacted the HCL help line and Airtel help line, and did as they guided me. but could not connect. I am receiving very low signals even if i am sitting beside the modem. Plz. Help. I