i have format ps3 after that i can not sign in any more
Welcome to the PlayStation Community.
What do you mean you can't access your account, what happens when you go to sign in?
If you're still having issues with this try the following.
Go to the far left of the XMB menu, choose users, then choose new user & choose add existing user, then add your original PSN ID & password you always used, you should now be able to sign in ok, you can if you need to go ahead & delete any others users on the PS3.