problem with Internet connection

I have desktop DELL with wireless adapter Belkin G connection. It worked normaly more then 2 years, but two weeks ago Internet connection stoped and permanent appears 'Acquiring network address' with moving yellow point around the icon.
I tryed a lot of advices, but recently discaver that my DHCP service and TCP/IP doesn't work. When I try to start them through 'service list', message appears:
'Could not start the DHCP Client service on Local Computer. Error 1075: the dependency service does not exist or has been marked for delition.'
Please help!....