Pay attention to the case of input method.
The password has been modified.
"3" is infected with virus, so it is recommended to kill virus regularly.
〈 4 〉 The network is unstable, and it may be better in the future.
"5" QQ program error, you can install the latest version.
[6] The account has been frozen, so it is temporarily impossible to log in.
[7] The QQ number has been recovered by the system because it has not been logged in for a long time.
1 During peak hours, this number occasionally fails to log in.
This is a normal phenomenon
Please try again later;
There may be something wrong with your QQ version or computer program.
I suggest you download QQ again or try to do the program again.
Just fine;
Then your number may have been stolen.
You can get it back through your password protection and appeal.
If these two methods are still not found, there is basically no hope.
A, first of all, please check the firewall settings, it is recommended to temporarily close the firewall;
B, it may be caused by the adjustment of QQ system, so some segments can't log in. I suggest you try again later.
C try to use selective login server (there are three modes at present, namely UDP mode, TCP mode and member VIP mode).
Operation method: Set the advanced settings in the lower left corner of the login window-select the login server, and then select UDP mode, TCP mode, and member VIP mode (members only);
D, it may be that the agent you used has expired, and you can work normally by changing the agent or not.