CoBrentwood--
Do you know what the source or content of the .adp file is? It could be a Microsoft Access file. Access would open it in that case. Or it could be a .txt file and Notepad|Wordpad would open it. Or you could convert the .adp file to some other extension that you can open.
This is all discussed in detail here http://pcsupport.about.com/od/fileextensions/f/adp-file.htm
As you can see there is more than one possibility.
Do you know what the source or content of the .adp file is? It could be a Microsoft Access file. Access would open it in that case. Or it could be a .txt file and Notepad|Wordpad would open it. Or you could convert the .adp file to some other extension that you can open.
This is all discussed in detail here
http://pcsupport.about.com/od/fileextensions/f/adp-file.htm
As you can see there is more than one possibility.
http://filext.com/file-extension/ADP