Which OS, Browser you are using ? What is the name of the file that you are trying to install ?
Please post a snapshot of the error message you are seeing using The specified item was not found.
Windows 7 64-bit. Firefox. I tried doing a clean uninstall, followed all those instructions, didn't help. I made a jpeg and a png screenshop of the error message, but this current message will not allow me to insert it. It says "That image type is forbidden."
My Flash Player error message says "Insufficient user privilege to install application.”
The name of the file is install_flash_player, downloaded right from get.adobe.com/Flash Player
Now I am getting a more detailed error message that says:
A required file (C:\windows\SysWOW64\Macromed\Flash\flashplayer.xtp:5) could not be written due to insufficient permissions.
The number 5 in the error message is a Windows 'Access is denied' error code. The Access is denied error prevents the file from being deleted and the new version installed. This generally means there are permissions issues on the file itself or in the registry. In this case, most likely on the file. This can be caused by any number of things. Please see the tech note Flash Player | Windows registry permissions for information on how to fix the permissions.