The Windows AutoPlay system is quite complex and its behavior depends on a lot of registry settings.
Unfortunately, the AutoPlay Control Panel applet in Windows 7 doesn’t allow you to change system-wide settings. So it’s possible that ”Use AutoPlay for all media and devices” is checked, but AutoPlay is still disabled.
To enable AutoPlay use either of the following methods:
Using Group Policy Editor
Open Local Group Policy Editor (gpedit.msc), navigate to Computer Configuration / Administrative Templates / Windows Components / AutoPlay Policies and change the Turn off AutoPlay policy to Disabled.
After that you can reset it to Not Configured, which is the default state.
Unfortunately Group Policy Editor isn’t available on Windows Home editions, as an alternative you can use regedit.
Open regedit and locate the following key:
change (or if it doesn't exist create a new DWORD)
For more information please read the following KB article:
How to disable the Autorun functionality in Windows