Well there is no need to uninstall ALL software. It would need to be software you could logically reason might affect your registry or services related to Autoplay. For example I use TuneUp Utilities and I know it tweaks registry settings so I would consider uninstalling that but I also use Microsoft Office: Word, Excel, Powerpoint, Outlook and I am confident the office suite would have no effect on whether my Autoplay worked or not.
If you computer has other issues too then the best bet is probably a fresh reinstall of Windows 7 but doing that would also be a problem for you because you would need your missing programs disks. Depending on the software you might be able to download it. Note, for software that requires a product key, make sure you extract the key before you erase or reinstall from/over your current installation.