.jpeg should open with any photo program like Photo gallery, Faststone picture viewer and alike
.pdf should open with Adobe or Foxit
I suggest you have a look into your file associations table and check which programs are associated with these filetypes. If necessary, change it.
If that is not something you want to do, download these 2 programs and they will automatically set the associations: Foxit Reader - Download FastStone Image Viewer - Powerful and Intuitive Photo Viewer, Editor and Batch Converter