ok sorry i wasn't really specific but its right when i am signing in when i get this error message saying " could not connect to Stem network " and i have contacted steam support and they refer me back to this page https://support.steampowered.com/kb_article.php?ref=6776-MYXU-0480 and i have already tired this before and it didn't make a difference. I have searched the internet for some time now and i haven't seen anyone who has had this problem before.
When was the last time you connected to Steam? I had the same issue like yours when I tried to connect to steam after I bought Civ 5 before which I haven't connected to Steam for several months. I tried all the methods like what have been suggested above and by steam support but non of it worked. So, what did I do to end this plight? Great patience is needed at here. All I did was connect, re-connect, connect, re-connect, then close your steam program and restart, connect and connect again until....Steam is really got connected to steam server. What the real problem is simply you're really in a bad luck and got caught in server's traffic congestion (you know that currently Steam has a thanksgiving promotion).
Anyway, if you've tried several methods including deleting the clientregistry.blob file, then you can just stop doing whatever you've done. Just be patient and let your steam connects by itself. It will do eventually (my experience, it may take half an hour or to hours, it really depends on your luck, steam server status and your internet connection)