Hi,
This looks like a multi-screen problem. The software keeps track of the position of the window, so if a second screen disappears, the window may be outside the remaining screen.
You can try to put back the second screen (if it's the case) or delete the file that holds this info, but you'll lose other information stored in this file: C:\Users\yourUserName\AppData\Local\Paint Of Persia\User DataDefault\settings.json