Populate PDF files in listbox on usrform based on selected device from combobox

[MKLAQ]

Hello
I search for maro to do many requiremns .
1- combobox1 should populate devices C ,D,E
1- combobox2 will show all of folders for slected device from combobox1
2- the folder is selected from combobox2 based on selected device from combobox1 contains PDF files , also contains subfolders Naturally contains PDF files
3- should populate folders in combobox2 based on selected device from combobox1.
4- when select folder from combobox2 if the selected folder contains folders then populate the subfolders in combobox3.
5- when I select subfolder from combobox3 then should populate PDF files in listbox1 .
6- if I select folder from combobox2 and doesn't contain subfolders in combobox3 then populate PDF files in listbox1 based on selected folder from combobox2.
7- when populate PDF files and click for selected item from listbox1 should open the PDF file.
8- when open PDF file I would show message to print out the file , if click ok then print out . if click no then keep the pdf file keep showing without print out.
thanks in advance