To get back RSTRUI.EXE, you must do dism /online /cleanup-image /scanheath, then dism /online /cleanup-image /restorehealth then sfc /scannow. This may take a while but the system files will be restored. If not working for the restorehealth argument you will need to specify the source. for sfc if you can't repair the files do it at boot. You may need to reinstall some hotfixes and updates. or go in the syswow64 folder in the C:\Windows and find rstrui.