It's very simple, just follow the steps below :)

>restart your PC
>open Steam and log in
>launch DOTA 2
>DO NOT CHANGE any settings in the game (graphics settings should be the same as before the patch)
>start solo game with bots

This is the most important point of the guide, because after patch 7.36 the problem is that the map takes too long to load. This makes it impossible to join the match. Loading a match with bots (in solo queue there is no time limit for joining the game) causes the map to remain loaded in the game's memory, which shortens the process in subsequent matches.

>stay in the match with bots for ~5 minutes
>quit the match and voilà
>now you can safely search for a ranked game, everything will work as before

Have fun :D