Excel Import need help

I have imported a masive amount of produt but the SKU will not import with the excel file. I exported the one test product to give me a template and used that, if I try to import the same producyt it simply adds another instead of updating. I noticed the sku is missing and wont import aswell.

I am using nop 2.3 on godaddy. the test product will update but the unes I am importing will create copies if i import the file multiple times.

Just figured out the cell has to be in text not mumber, tried changing it to text but still wont work without a letter or symbol in the field, any idea how to avoid this or am i going to have to add letter to the sku

Yes, although SKUs are typically digits, but it needs to be a string.
There is a caveat in Excel's data reader  - it only examines the first 6 (I think) rows to determine the data type.  So, if your first 6 rows have numeric only (or blank), and then later rows have other types, then you could have problems.
Try including a leading single quote '