Having enabled "Internet Connection Sharing" in the first PC (which will configure its Local Area Connection with the IP address 192.168.0.1), you need to set the other computer to get its IP address automatically. Right click its Local Area Connection, select Properties, highlight the entry for "Internet Protocol (TCP/IP)" and click the Properties button. Select the options for "Obtain an IP address automatically" and "Obtain DNS server address automatically". The second PC will then get its addresses by DHCP from the first PC - the one whose internet connection has been shared.
You may need to change the settings in any firewall software you are running to take account of the changed IP addresses before your local network will work again.