CS:Go doesnt launch/start anymore

Today Cs Go patched and know it wont start anymore. I click on start game then the window appears with Counter Strike Gloabal offensive is starting. The window disappears nothing happens for some seconds and then I see in steam on the right side of Cs:GO "Synchronizing". It always started before this patch. I restarted steam. Does anyone have an idea. btw the game doesnt even appear in the task manager