Products disappeared

I deleted my inventory since I was changing the descriptions, etc. of many items. I then tried to upload a new inventory using ezpopulate. The categories appeared, including a new one, but non of the products are there. This was the exact same ss that I had used previously.
Anyone possible help?

Do you have unique product numbers and are the last two fields coded 1 and EOREOR, respectively, for EACH product you want to upload?

Tina

Thank you for spending the time to help. I had changed some of the info on the ss I previously used and had some items on the site that ere no longer prevalent. SO I deleted all the items on the categories area, then attempted to download the original ss with the changes. However, this time not one item showed up.