I created a design in Inkscape and I was having an issue with the design converting to PDF. The problem is whenever I export it to PDF, the blurred shadow disappears in the PDF file. I need this solved ASAP because I need it to send it for print. I hope you understand.
Inkscape's effects can suffer when you make a PDF. That depends on used PDF engine and settings. The same problem has occurred also with blending modes:
As a first aid try to insert the shadow as separate object. Rasterize it. Edit > Make Bitmap Copy generates a rasterized copy. Set the rasterizing resolution high enough in the preferences.
If you select 'rasterize filter effects' in the pdf export dialog, the filter effects will be carried over into the pdf file. I suspect that you accidentally unchecked that box (I believe it's checked by default).