In half life 2 which is the cheat that takes you to the chapter after ravenholm

First, you have to complete the whole game. Then, click new game. Last, click on the chapter after Ravenholm. If the option to choose this level is not present, simply open the developer console (Pressing ` or ~) and type in "sv_cheats 1; sv_unlockedchapters 8" without the quotes. This will take you to the beginning of the chapter "Highway 17". This cheat can be used to unlock all chapters by entering "sv_cheats 1; sv_unlockedchapters 14".