1)i download opn2.2.2 and i unzip it and i start the installation but it didn't let me choose installation lang. why ?

2)then i do the installation in ger and i go and change the lang to en but it didn't change anything

3) i am working in opn2.0.1. what can i do to update to opn2.2.2?the update file change enything in db?

1.) a simple bug - its fixed for next release
2.) that should work
3.) AS a very first step you should backup your database. If anything goes wrong in the following steps, you might be able to start over again

a) login to your site
b) copy all new files to your web ( i would recommend to upload the full 2.2.2 package
c) now when going to your site you will see many errors and warnings - don't worry.
d) go to admin->diagnostic->repair the pluginfeatures
e) go to admin->Moduleupdate->automatic moduleupdate
f) have a cup of coffee while opn is updating (automatic redirection) - opn will tell you if it's done
g) repeat from step d) until all messages are gone
h) go to admin->diagnostic->repair the settings
i) There might be the need to run the other diagnostic repair functions - this depends of your site

Alex