populate pdf files in lists based on dropdowns for month into two sheets

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Hello
I have two folders are PURCHASES & SALES in this directory "C:\Users\lp\Desktop\REPORTS"
the PURCHASE & SALES folders contains months folders like JAN ,FEB... and every month folder contains PDF files
so if cell M2 is empty , then should populate the whole of pdf files with hyperlink to open under each month based on matching headers
and when select M2 the month from M2 then just show month within year. so I put two cases as in examples .
should implement for two sheets (SALES,PURCHASES).
thanks

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I need help .

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my request is not clear despite of I posted some examples inside the sheet?