1st you must check patch version:
Type version in game console   ~ (tilda)  , Ё (rus)

If your patch version is below 2.0.7.5, download and install this patches in left 4 dead 2 folder on your pc: (it takes about 1 hour+ minimum for downloading and installing all patches) 
if your patch version is between 2.0.7.5-2.1.0.0, use this patch instead of master patch 2.1.0.0   2.0.7.5-2.1.0.0 elite and then continue 2.1.0.0- to latest  or  2.1.2.6 Full Game then  patches from 2126 to latest 
                                                                                 or
GAME 2.1.3.9 Version. http://kickass.to/left-4-dead-2-v2-1-3-9-autoupdate-multilanguage-no-steam-orangebox-t10188942.html#main
​You will need only standalone and shortcut settings 
 

 

1)	Master patch 2.X.X.X-2.1.0.0 2.3Gb	from any version to 2.1.0.0 (To install this patch, press "Master2100.exe".
2)	2.1.0.0-2.1.2.0
3)	2.1.2.0-2.1.2.3
4)	2.1.2.3-2.1.2.5 (1.4Gb)  or 2123-2125part1 and 2123-2125 part2
5)	2.1.2.5-2.1.3.2

6)  2.1.3.2-2.1.3.3

7) 2.1.3.3-2.1.3.4

8)  2.1.3.4-2.1.3.5
9) 2.1.3.6-2.1.3.7 
10) 2.1.3.7-2.1.3.8 
11) 2.1.3.8-2.1.3.9 

12)  Standalone 15.5

 

     YOU CAN ASK QUESTIONS HERE