"Dependency service or group failed to start" and unable t..

My access to internet failed since yesterday. I checked and all hardware
are working properly. I've done researches and so far, and still no
luck, here's what I have done so far after the problem exist:

1) tried to use scannow on cmd, no error found
2) installed SP1 on my Vista as some people said it may correct the
problem but it does not, and it also erased all my previous restore
point that I could use and may have fixed the problem?
3) replaced nlasvc.dll per some suggestion I found online, it's not
working either
4) When I opened IE and obviously it'll say connection problem. So I
clicked "Diagnose Connection Problems", it says "Network Diagnostics
cannot run because Diagnostics Policy Service is not running". So I
opened the Service Manager and tried to start the Diagnostics Policy
Service manually, it failed with mssg: "Error 5: Access is denied".
5) Some peopel say it is the corruption in the TCP/IP Stack, so I tried
command Prompt type : netsh winsock reset and reset, not working.

Any suggestion is highly appreciated. I really hope to fix this without
having reinstall the OS

Thanks!

P.S. Just remembered something.... the only incident in before and
after the problem is, the power failure in my house area, while my
computer was plugged in and running without a battery inserted. I'm not
sure if that accident shut down is the cause of this problem or not.