More information and clarification is needed. Is there an .imsorry extension also appended to the end of your JPG files? If so, you are dealing with ransomware. Im Sorry Ransomware displays a message which offers to decrypt files if a ransom payment in Bitcoins is made to the criminals.
Is there a Ground.exe program running in your Startup programs or as a process in Task Manager. If so, other victims have reported that it was related to downloading a program called Dark Souls III. See here.