If you a re computer addict, then you probably know most of the keyboard shortcuts mentioned here, and you also realize that keyboard shortcuts save more time than using the ‘Mouse’ to get your work done :). So it’s obvious that they improve your productivity as productivity is directly proportional to saving time 
.. eeesh… Let us look at some of the most important and commonly used Keyboard shortcuts which will improve your productivity…
1. Windows System Keys:
* F1: Help
* CTRL+ESC: Open Start menu
* ALT+TAB: Switch between open programs
* ALT+F4: Quit program
* SHIFT+DELETE: Delete item permanently
2. Windows Program Keys:
* CTRL+C: Copy
* CTRL+X: Cut
* CTRL+V: Paste
* CTRL+Z: Undo
* CTRL+B: Bold
* CTRL+U: Underline
* CTRL+I: Italic
3. General Folder/Windows Explorer keys:
* F2: Rename object
* F3: Find all files
* SHIFT+DELETE: Delete selection immediately, without moving the item to the Recycle Bin
* ALT+ENTER: Open the properties for the selected object
* F4: Select the Go To A Different Folder box and moves down the entries in the box
* F5: Refreshes the current window.
* F6: Moves among panes in Windows Explorer
* CTRL+G: Open Go To Folder tool
* CTRL+Z: Undo last command
* CTRL+A: Select all items in the current window
* BACKSPACE: Switch to the parent folder
* SHIFT+click+ Close button: For folders, close the current folder plus all parent folders
4. Windows Explorer keys:
* Numeric Keypad *: Expand everything under current selection
* Numeric Keypad +: Expand current selection
* Numeric Keypad -: Collapse current selection
* RIGHT ARROW: Expand current selection if it is not expanded, otherwise goes to the first child
* LEFT ARROW: Collapse current selection if it is expanded, otherwise goes to the parent.