I am new to opencart and these forums so please bear with my silly questions

I am running opencart on my website along with a template developed by imaginetech (proshop).
Now im having problems in Admin, firstly when trying to edit a product the information available to edit in the 'General' tab has completely dissapeared. The strange thing is it will appear for half a second then dissapears and leaves me with a small empty box. The other tabs work fine. Note I have already set up my products so this was working previously, im not sure what has changed. When viewing the products on the site itself I can see all the info no problem
I have recopied all of the admin product.tpl files so I dont think the problem is in the code, is there a flag somewhere in the database maybe to hide this information?
Also I uploaded an image which appears to have been too big, and now I cannot see any uploaded images when trying to edit product images/logo. Can anyone tell me which database table holds the logo image so I can remove the large blob data and hopefully solve the issue?
Is there a link somewhere to the database structure?
Thanks in advance
