My OS: Windows 7 Home SP1, no install DVD, only recovery possibility on laptop HD. So it happened - the disaster. Because my LAN connection didn't work, I have started to change folder permissions of the whole 'Program Files (x86)' folder by going into Program Files (x86) > Properties > Security to set ownership to my only Admin Account, adding 'Administrators - COMPUTER NAME' into the permissions section, both with full access rights. The result of all this: I cannot access anymore some programs and their files ("You do not have access rights...", some programs installed don't work anymore, I cannot re-install or repair them using the Program Deinstallation section in Windows. I don't even recall all exact steps I have done, I know now that this was a very bad idea and I must revert everything for my computer to work right again. I was able to reset the 'Freigabe' tab settings in the folder properties in order to be like before, thus denying any external access, but I cannot revert the 'Security' tab settings to their defaults. After googling long and large, I have used the tool here to solve to no avail: https://shurikenskribbles.wordpress.com/2018/06/13/restore-file-permissions-default/ This tool doesn't work, I get a lot of "Not a valid Handle" messages ("Das Handle ist ungültig"), as well as some messages with "Access Denied", and all was not changed. A bad coincidence is: My restore points of Windows all seem to end-up with an error message (0x8000ffff), also in Protected Mode, so I will continue to try other restore points (very time-consuming), but I plan not to receive any help from that. Questions: Can I just repair the folder 'Program Files (x86)' ? How? What options do I have to restore Windows without deleting all my software and personal folders / files ? I thank you very much for any ideas and HowTos !