common problems with network interconnections
When a computer system cannot connect to the network, the following is what should be investigated. For the following, the assumption is that a prior connection was possible.
The connection is no longer complete. Someone has disconnected the cable at one of the two ends. Cable replacement with good one will allow this situation to be checked. In some circumstances such as a Thin Ethernet Cable Bus network, a break in the continuity or a missing terminator will stop the network from working properly.
The network card is dysfunctional. This can be tested by replacing the card with one that is known to work.
Network connection software incorrect. If the software installed on the computer becomes corrupted, the system will not connect to the network. This requires a full installation of the software onto the system.
Mike Leishman