I have really BIG problem with my n900 wifi. After some browsing just stop working. When I flasing that nothin chenge but I thin flasing don't chenge all data in N900 f.g. history browsing or bookmarks ar still hire and other settings but not all just a bit. I was using WIFISwitcher and maby that mess up my n900. I can use gsm network and when I try to find network that tell me is no any network. Sometimes pop up system message like some file is brooken bot only when I try to swith the wifi on.
Any ideas how to fix it or how to flash n900 completly ?

It sounds like you didn't really flash it. Try this guide:
http://wiki.maemo.org/Flashing#Updat...ng_the_Flasher

run the following command in your terminal
" sudo ifconfig | grep -i wlan0 " and see if you get an output or not.

you can paste the output here (remove the hw address value though)

ok then:

@Path - I've done this command under the gainroot and was displaying nothin, just next line to write.

@MiK546 - i,ve done flashing like in this instruction just my batery was not half full but everything goes right.

Maby I heve to give to my provider for repair but I really don't wont to stay with out one week

no one know ? ehhhh I stay alone with my problem.