Hi to everyone!
After the upgrade of my forum i start to do some changes and at the beginning i didn't have any problems with my login!
The last thing that i did in the ACP was something which is called persistent login and mistakenigly i deactivated and now i try to log in and when then page redirects the board logs me out
What should i do to get it fixed

Typical cookie problem, first go to your /acp control panel and save the domain settings under Applications. If you still have problems, clean temp files and cookies in your browser.

Unfortunately nothing worked!!
I cleand the cookies and the temp files.
I tried from another pc with different ip and still does the same.
Moreover when i click to a post as a guest only a message appears which says:

General Problem

SQL ERROR [ mysqli ]

Table 'roadclub_phpbb24_com.phpbb3_gallery_users' doesn't exist [1146]

An error to the database appeared through the creation of this page

I don't know what i did wrong

Have you activated the gallery?
Can you send me you login details in a pm so I can check the login?

Yes i did!.
I shouldn't have done it?
I did it because i saw your post about the gallery!

Well, you activated the gallery option where you convert the phpbb2 gallery to the phpbb3 gallery, and you did not follow all the import steps, that's why you got this error.

And now what?
Can you fix it??

I reinstalled the gallery, and in your /acp I have resetted the styles, since the style that you choose is not working, you have to choose another style until that style is fixed.

So it was the style's problem!
Thank you so much for your help!!!
I'm so glad everything work again!!