How To Reinstall the Adobe Reader Plugin
Adobe Reader is a free portable document format (PDF) viewer. When you first install Adobe Reader, the program automatically installs a browser plugin that allows you to view and print PDF files directly from your browser. If the current installation of the plugin causes your browser to crash, you can reinstall the browser plugin file, located in the Adobe Reader program file folder. If this does not resolve the problem, you can completely remove and reinstall Adobe Reader, which will reinstall the browser plugin.
Show Hidden Files and Folders
Click "Start" and select "Computer."
Click "Organize" in the file menu then click on "Folder and Search Options." A new window will appear.
Click on the tab that reads "View" then scroll down to "Hidden Files and Folders" under "Advanced settings."
Select "Show hidden files and folders." Remove the check marks next to "Hide extensions for known file types and "Hide protected operating system files (Recommended)."
Click "OK" to save your settings.
Reinstall Adobe Reader Plugin
Right-click the "Start" icon and select "Explore" to open Windows Explorer.
Navigate to the Adobe Reader installation folder at "C:\Program Files\Adobe\Reader 9.0\Reader\Browser" by clicking on the folders in the left pane.
Locate the "nppdf32.dll" file in the right pane. Right-click the file and select "Copy."
Navigate to "C:\Program Files\Internet Explorer\PLUGINS" if using Internet Explorer or "C:\Program Files\Mozilla Firefox\Plugins" if using Mozilla Firefox, by clicking on the folders in the left pane.
Right-click anywhere within the folder in the right pane and select "Paste." Click "Yes" when asked if you want to overwrite the file.
Reinstall Adobe Reader
Click "Start" and select "Control Panel."
Click on "Programs and Features" if using large or small icon view or "Uninstall a program" if using category view.
Scroll through the list of installed programs and locate "Adobe Reader" in the list. Click "Remove." Allow the computer to completely remove Adobe Reader from your system.
Open your Web browser and visit the Adobe Reader download page (see Resources). Click the gold "Download Now" icon on the Web page. Save the file to your desktop.
Double-click the installation file on your desktop. A dialog box will appear.
Click "Next" then click "Install." Allow the installer to unpack and reinstall Adobe Reader on your computer. The Adobe Reader browser plugin will reinstall along with the program.