Codeigniter Website Repair: Users and Articles continue to disappear

Something strange is taking place with my website. (The website is written in CodeIgniter) : Several days ago Users and Articles began to disappear. So, the task is: - to find the reason and fix it (taking measures to prevent such things from happening again) - update CodeIgniter 1.7 to the latest version of CodeIgniter (converting Plugins to Helpers and so on ) - add in an admin panel possibility to change a password for an admin panel (before to change an admin pass, a user should fill in an old pass). - several minor amendments described in the attached file [login to view URL] Due to limited budget I'm ready to pay up to $40. As the website needs many features to add in the nearest feature, I hope for collaboration on a constant basis. This project is an excellent opportunity for a freelancer to get an excellent review. The bid with lower amount will be preferred.