How to solve ‘You do not have sufficient permissions to access this page.’ in WordPress

Network Admin menu is not Visible and disappeared  in wordpress Dashbaord ?

I had installed wordpress multi site and  i decided to change my wordpress Amin user name with something new because it is a good idea to have something different user name than default admin. In case of Admin bad people already know your user name and they just need to your password to damage your website.

Here is a guide How to Change WordPress Admin user name ?  but after changing my admin name Network Admin menu was disappeared from wordpress dashboard.
Even when i tried to access directly by typing
network admin address in browser location bar i got following error
‘You do not have sufficient permissions to access this page.’
I tried to find the solution on google but i failed to ind the answer, then i decided to change my new wordpress Admin user name with previous name that was Admin. So i followed the instruction How to Change WordPress Admin user name ? and set user name as Admin.
After setting old user name Admin i logged in successfully to wordpress dashbaord with user name Admin and my password and Network Admin was visible again in dashboard.
Note :
I am not an  wordpress expert but i always try to learn new things about wordpress, if you have solution of this problem please share in comments.

Update :

If you WordPress multisite installed, than you will have to change WordPress multisite admin user name. Read How to change  WordPress multisite admin user name ?