Set "Computer" folder to its original view style in Windows 7

It looks like you've hidden the navigation pane. To make it re-appear, try:

"Organize" -> "Layout" -> "Navigation Pane"

You've set the view to "Medium icons".

To fix:

Right click, View, Tiles

1. In the Registry Editor (regedit) backup/export the following key first:

   HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell
   

2. Delete the following key:

   HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\BagMRU
   

3. Restart

Note: This will reset all your folder customizations.