HI,
There could be many reasons for your issue, but it looks driver issue. (if we assume that have network card in your machine)
First, please check that your hardware is on the compatibility list (link was already shared before)
Second, if the server is on the list, and you are aware of the hardware vendor, please download and use the vendor specific esxi installer image. It can be downloaded from VMware or the vendor site as well.
Third, if the hardware is not supported, you may try the community nic driver from flings site.
Otherwise, please share more details for better understanding you environment.