You can't recover the files if you uninstall the program from your computer and I suggest you download and install the software back to your PC. After that, navigate to Control Panel > Appearance > Folder Options, click the View tab, check the Show hidden files, folder, and drives box and click OK. In the Search programs and files field from the Start menu type
win_mpwd_sys.dat and delete all the displayed files. If it doesn't help, try to contact the developers.