1. Type regedit in RUN or Startmenu searchbox and press Enter. It'll open Registry Editor.
2. Go to following key:
If the above key doesn't exist, create it.
3. In right-side pane, create a new DWORD value NoDriveTypeAutoRun and set its value to any of following according to your requirements:
FF - To disable AutoRun on all drives
20 - To disable AutoRun on CD-ROM drives
4 - To disable AutoRun on removable drives
8 - To disable AutoRun on fixed drives
10 - To disable AutoRun on network drives
40 - To disable AutoRun on RAM disks
1 - To disable AutoRun on unknown drives
4. If you want to disable Autorun on a combination of drives, you'll need to calculate sum of the values. For example, if you want to disable Autorun on CD-ROM drives and removable drives, you'll need to set the value to 20+4=24.
5. If you want to restore the Autorun functionality, simply delete the NoDriveTypeAutoRun DWORD value created in Step 3 Or you can set the default value which is given below:Windows 7: 91
6. If you want to disable Autorun functionality for all users in your system, use the "HKEY_LOCAL_MACHINE" instead of "HKEY_CURRENT_USER" mentioned in Step 2.