wp-admin privileges restricted

My wp-admin folder’s chmod value is 755 and after i login (with one that has admin access), some functions aren’t visible. There isn’t a “Users” menu in the left anymore. I can’t add any plugin via that panel. The most important for me is i can’t edit widgets. Some missing stuff like these.

I also made mysql table’s names starts with something other than wp_ and set capabilities as administrator and user level as 10 for my user. Isn’t that the highest permission?

So i know it’s more secure that way but i just want to get those functions back in the menu at least when i need to change something quick and simple. How can i see wp-admin at full capacity?

Thanks.