Fix the admin section of my Zen Cart Site

Hello, After someone did some work on my site it seems that some of the old functions are no longer working. I would like someone to fix these for me please. In the admin area of the site when something is changed it no longer saves into the database. I would like this fixed. The most important things I would like fixed are: - The stock levels to decrease when something is purchased. - When metatags are added to a product they are saved. - When image is added to a product in 'image handler' it is saved. The above is only some of the problems with the site. Basically, I would like it so that when something is saved in the admin sections it actually saves!! At present, everything does not save and I get redirected to the admin homepage. To get information saved at present I need to go directly through the SQL myadmin which I no longer want to do. Please could someone fix the problems in the admin for me. Website is: [login to view URL] I would prefer someone with experience using zen cart so please let me know if you do when you place your bid. Many thanks, Gary