Steam games wont launch after downloading

I'm not very good at stuff like this, but after I've downloaded any game, it will just pull up the launching menu, close and then nothing happens and it prompts me in steam with the launch button again. I've restarted my computer multiple times, deleted the games and redownloaded, deleted steam and redownloaded, going into download content settings and repairing the downloads, and nothing seems to be working-- please help!