connected to a public network with a limited connection

hi there, suddenly on my hp desktop i couldn't access the internet so i troubleshooted the connection and it always says " investigate router or broadband modem issues " and asks me to reset the router i did it so many times but its not effective and it always says im connected to an unidentified public network " in black color so can't be changed " :mad: so what do i do ? notice i have...