Question: I copied 3.62 GB of data on to a re-writable DVD instead of erasing it. Now there is no data on the disc but it shows used space as 3.62 GB and 690 MB of free space. Now I am unable to erase my disc. What should I do to erase the disc and get the space back?

Answer: 
if you don't want to install additional software, use **[InfraRecorder](http://infrarecorder.org/)** Portable.

Go to **Actions** > **Erase/Format Disc...**
As stated elsewhere, you need to erase the DVD-RW before using it again. I have a very simple low profile program I use called Active@DVD Eraser located here:<http://www.ntfs.com/dvd_eraser.htm>