Repair Existing Wordpress Website

My Wordpress site has some issues that I need fixed. Here they are: 1) I can't publish or update posts or pages. There are no Publish buttons or Update buttons showing up in the admin dashboard where they normally would, when the admin is trying to add or publish a new post or page. This is not because the boxes or buttons are hidden or have been moved to another spot on the page - they are completely gone, so must be restored. 2) When I try to adjust the settings on any plugin currently installed on the site, I get the (pretty common) Wordpress error message: "You do not have sufficient permissions to access this page". Of course, I would be logged in as an admin, so there is no reason for this error to appear. I used to have the S2Member plugin installed on the site and recently removed it, so I'm guessing that this plugin messed up roles and permissions - but that's only a guess. I have tried to adjust admin rights and permissions in the MySQL database using PHPMyAdmin, so I've already done some pretty technical stuff. In addition, using a plugin like "User Role Manager" only gives me the error message above. So you'll have to be creative here. 3) When I try to view my pages or posts within the dashboard as admin, I get the message: "No posts found" (or "No pages found"). This error shows up even though there are hundreds of pages and posts stored in the database. Here's a clue: if I change the Permalinks in General Settings to the Default Permalinks setting and Save it, I can view posts or pages from the Dashboard (but not from the side menu). However, the Permalinks can not be left in Default settings for this site, that will kill my SEO. So help here would be wonderful. A little background: I have had a number of plugins recently removed from the site including the S2Member plugin I mentioned, also, "Peter's Login Redirect" and "Securi" security plugin. Not sure if removing these caused problems, but possibly. I also manually edited the htaccess and wp-config files but perhaps more editing is required. I DO NOT want the database to be restored. I don't necessarily think doing so will solve these problems. I believe the fixes lie within some PHP tweaks, but I don't know which files need to be fixed. Please do not bid unless you are a stellar Wordpress and PHP expert, as I'm pretty knowledgeable myself, but need someone who knows more than I do! Thank you for your time and good luck.