How do I convert Easting/ Northing GPS coordinates into Lat/Long?
 

I have an easting and a northing coordinate for my point, but I need those
numbers in Lat/Long. So far I have found 50+ page papers online, and then
download-able products that do not work so I don't know where else to look.
How can I do this in Excel? Any other thoughts?! Thank you!

How do I convert Easting/ Northing GPS coordinates into Lat/Long?
 

I found this site:
http://www.gpsy.com/gpsinfo/geotoutm/

....which has a couple of XLS files available for free download.
There's one at the bottom of that site that appears to be what you
need:
http://www.gpsy.com/gpsinfo/geotoutm/utmconversions.xls

Good luck with it!