i was surfing the internet and all of a sudden i was asked
to join a new network:169.254.78.92 with this ip.
i just closed it but what is this network? i tried to look it up but without success.
also, it knocked out my ability to surf the internet on that computer.
Your PC was simply unabled to renew its address with the DHCP server hence the network in the range 254.xxx.xxx.xxx. Have a look here : https://forums.comodo.com/firewall-help-cis/new-private-network-notification-t77988.0.html;msg557680#msg557680
Addresses in the range 169.254.0.1 to 169.254.255.254 are called APIPA (Automatic Private IP Addresses). An address from this range is dynamically allocated when a DHCP server cannon be contacted, even temporarily.
In your situation the IP address you had been using probably came to the end of it’s lease and had to be renewed. For whatever reason. the DHCP server responsible for allocating/renewing your IP address (your router?) wasn’t able to be contacted or did not respond in a timely manner, hence the APIPA address.