Don't dispair just yet man. You can reset the permissions using this tool. http://djlizard.net/...Permissions.exe
DL it and then it and save it somewhere you can find it like the desktop. Double click on the icon that appears and then click run. In the self extract screen, again save it to a location you can find and click extract. It will extract three files. One of the files is called !Runme or !RUNME.BAT Double click that and let it run all the way through. It will take quite some time so be patient.
WARNING: Be advised that the !RUNME fix is very intensive and will bog your system considerably. So it's best to click it and leave it alone until it's done. Don't worry. It won't hurt anything if you run it on a system that doesn't need it. All it does is return your permissions to default (which is what most systems are set to anyway)
NOTE: If you are unable to open .bat files because of file association problems, tap F8 while booting the computer, select "Safe Mode with command prompt" and navigate to and run the batch file from the command prompt.
If this doesn't work let me know what errors you get and I'll try and help. I know it's hard, but do be patient, the fix can take a while.