This is most likely a physical connection issue, USB not being plugged in all the way or plugged into the wrong port. Make sure the scanner is plugged into the computer. Try a different USB port.
If this does not solve your issue, then your problem might instead be the result of a hardware issue, such as a broken USB port on either the computer or the scanner. Try wiggling the USB port. If it is wiggly, and quickly switches from connected to not, then it could be broken and require repair.
A potential issue is for the USB port on the back of the scanner to not be fully fixed. This can limit any kind of good connection to the data board inside. In a worst case scenario, the USB port is fully snapped off and rolling inside.