If your permissions in windows 7 get messed up, you can:

1. take ownership of all files, recurse, specify default answer to whether or not take ownership to y

takeown /f . /r /d y

2. give everyone read permission

icacls . /grant:r everyone:r /t /c /q

3. grant and replace existing permissions and give yourself full control, apply to subfolders too (/t) , continue on errors (/c) , and suppress success messages (/q)

icacls . /grant:r<your user id>:f /t /c /q