For a computer to open any file, it needs to have a program associating it with that type of file, so if a computer does not open a JPG file, the computer needs an associated program. Once this is in place, the computer opens that program any time a user directs it to open that sort of file. This is the same requirement whether one is trying to open a picture, word processing document, spreadsheet or other attachment.
In Windows, the best way to set up an associated program is to right click on the file. When the menu of options pops ups, the correct option to select is Choose Default Program. Most computers have software pre-installed that allows users to view and open JPG files, such as Paint or Windows Image Maker. Both of these open JPG files and permit computer users to make changes to pictures as needed. If a computer lacks a compatible program, another option is to search the Internet for a downloadable program that works with the specific file type. If the user has an active Internet connection, searching for a program to download that works with JPG files should only take a few minutes.