I have a Windows 7 computer. My boss changed the IPv4 address of this computer. Now, although all computers can connect to the network, they can no longer see this computer. And this computer cannot connect to the other computers.
I guess the first question you must consider is why he made the change, security for something special on that machine, something you were doing he didn't like, or does he not know what he is doing.
I would discuss it with him unless you want to put your job in jeopardy. It is simple enough to enter the network control panel and either change the address to a usable static address or to automatically obtain an IP from the gateway depending on the network configuration.