Hello.
Its not actually a gmod problem,but its have sites.
So,the problem is…It says that cannot log on in steam…I can start offline,or retry.Retry do nothing,butoffline mode works,but then i cannot play gmod!.Hl2:dm and tf2 too. 
Help please.
I tried all valve tips…Nothing helped.
Viruses:Checkes,none of them exist
all programs shut downed,even avg
And its still not working.I really apreciate your help.
P.S.Sorry for bad english,its not my first language.