To operate a computer on a network (including the Internet), you need to use a network card. There are a number of factors that can cause this device to fail.
One of the most common options is a driver error. To check, open "Start" -> "Control Panel" -> "Device Manager". Find the "Network adapters" section and expand it. If there is a yellow triangle (or question mark) icon next to the hardware you are using, the problem is most likely with the driver for that device. Right-click on it and select "Update Drivers". Next, select "Search for drivers automatically".
This problem can be solved in another way. Launch an Internet browser and go to the official website of the manufacturer of the network card you are using. Find the page dedicated to your model and download the required drivers. After the final download, double-click on the installation file and wait for the process to finish.
The second common cause is a disconnected connection. Select "Start" -> "Control Panel" -> "Network" ("Network and Sharing Center"). Find the network connection you are using. If it is disabled, open its properties and click the "Enable" button.
Another cause of malfunction may be the cable being used. Remove it from the network card and check for damage. Pay attention to the contacts - there is a possibility that some of them are broken off or come off the connector of the network card. If this is possible, check the cable functionality on another device. If everything works, then this is not the reason.
Crimping the used cable is another cause of failure. If the computer's network card is connected to a router, hub, etc., then a direct crimping scheme should be used. If there is a connection of one computer to another, then the cable must be crimped "on the contrary", according to the crossover scheme.
