my computer starts with a pic of a big question mark and under the apple icon is only"startup disk"What happened?

My ip address is not the same as my wireless printer,as a matter of fact the ip is a different address than mine.There is not enough disk space to download on this disk.I held down command and the r key,internet remote loading,then utilities I think I erased and reloaded os8 ,but at the end(it took 9 hours,is that normal,it could install.