If you have the backup folder from your previous installation, what you can do is replace the folder from the root folder.
Go to
C:\ProgramData\NCH Software\ExpressInvoice
If you can't find the ProgramData folder, set Windows to show hidden files and folders with the steps from this link: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files.
Just replace the folders and reopen the program, this should display all your information again.