Upgrade broke my shop. Urgent fix needed please!

Hi,
I've just updated to the latest version (2.1.0 from 1.5.6) because I wanted the 'proceed to Checkout' button in the Mini Cart, and that looks great now. But... I've found that the 'Add To Cart' buttons have all gone from every product (there are hundreds of them) and all the category listings have been changed to display one item at a time with pagination; one page per item. Before upgrade there was no pagination; all products were listed within each category.

So now I have a very urgent need for a very quick fix for this so I can get it all back to normal before the client notices!!!
VERY grateful for all advice offered.
Thank you
Cheers,
Frank

If a link is needed: www.chrissiedesignsjewellery.co.uk

ADDED NOTE: Ok, I've got the Ad To Cart button back on the products via Config/System/Display/General Display Options/Default parameters for products. Still stuck with the categories though.

Ok so I've found a solution to the category pagination issue. All category listings were set to a blank box for the number of products to display. Somewhere in my previous version - either by default or by a core file 'hack' that I can't remember - that meant that 'All' products would be shown. Not now though, so have put '500' in: Config/System/Display/General Display Options/Modules main default options. This isn't an ideal solution but it works.

So, topic can be closed or removed if of no use to anyone else