My wifi network stop working suddenly, need help

I have a wifi network in my home which was set up with my mac pro laptop. Suddenly it stop working, every time I try to select my network it gives me 2 difference errors, the first one is" A connection time out error" and when I go to network preferences and I select my network name from the big wifi networks, it connect for 10 seconds, all the green check lights turn on and suddenly i get an error saying something like" Network preferences have changed" and then all the lights go back to red, and the internet is gone. I have another wifi network set up that is still working but only if I'm in the area where the router is and I never use that bc the connection is fatal, every time that I used to change from my preferred wifi network it was working perfectly and in no time, but as of yesterday my preferred network does not want to connect, only my unpreferred network which I hate bc I have to watch my netflix from the sala instead of my bedroom. How can i make work my preferred network again? I just get the 2 error messages that I have described earlier. Sorry but I'm not a tech person and I have no help here from no one. Need somebody that can walk me thru. Maybe i change a setting or something i don't know.... Rookie Nicky from PR