[tretiak]

I have nokia n79. I was on internet using wlan and phone turn off. After I was tried to turn phone on phone ask me to type security code but I don't cant remember it. Now I can't turn it on because I don't know code. Do you know some way to reset phone to forget sec. code? 

PS Sorry on bad english

[kurtkaufman]

Try:

12345

I think that is the default security code.

[tiny_chef]

As what kurtkaufman have said, try first to use the default security code:12345. If you have customized your security code and unable to remember them, the only option is to bring the device to the repair facility to restore the code back into its default.