I was connectting to Internet normally,but when I installed some softwares or removed them,after that I restarted OS,I couldn't connect to Internet.Two small monitor at Taskbar have a symbol of excalamation point.I was using dynamic IP address,my card don't have any problems.And I tried typing static Ip address,restarted OS again,enabled the services in administrators tools,found any way to fix this but it didn't have effect.When I installed OS again,it didn't happen,but after that it happened again.I think maybe I removed some softwares and they had effect to OS .I don't understand why??Anybody know that please show me a way to fix it.Thanks very much!!!!

Have you gone into the control panel, system, hardware, device manager and checked if there is an exclamation point next to your Ethernet adapter(s)? If so uninstall them and restart the computer to reinstall them.

If the software that you installed/used/removed was spyware related,
you might find that Winsockfix helps.It restores something called the LSP chain.

The best solution is to avoid getting spyware on your system,if that is what the problem be.