How do I permanently get the net connection with usb 2.0 to ethernet

Hi,
During a thunder strike, the lan portion of my pc got damaged and as a alternative, bought usb to ethernet adapter 2.0 connector.
The drivers were not automatically recognized and one has to download the drivers for it to work.
The network is not stable, in the sense, that after one or two days, this usb port is not recognized and so no network connection, with the trouble shooting alert Please pllug a ethernet plug to the pc.
The recognition is not automatic in the usb to ethernet connection.
Why this problem and how do i permanently resolve it to get stable internet connection as I would have got , had the lan port not been damaged.
When doing research, I find that there has to be a separate device shown in device manager along with the network adapter to get this connection properly. Sometimes, the usb device is not showing and red light in the usb not glowing, and the ethernet lilght not glowing in the modem/roter.
I also find, that the VIA usb drivers , three devices shown as in the last three items in the usb ports, gets yellow exclamation marks sometimes.
please give a good solultion.

Hi, I think that I have not given the correct explanation.
Please see the device manager.
There is one entry,
rd9700 usb 2.0 to fast ethernet adapter. This device is not shown,even though it is plugged.
In the event of lan port is totally damaged , I bought the usb to ethernet adapter and it does not work correctly. When I plug a pendrive, it works. So there is no problem in usb ports.
I am enclosing the new adapters so that some one give solution.