Restart a wget download which got stopped in the middle using the wget -c option as shown below.
wget -c http://www.openss7.org/repos/tarballs/strx25-0.9.2.1.tar.bz2
This is very helpful when you have initiated a very big file download which got interrupted in the middle. Instead of starting the whole download again, you can start the download from where it got interrupted using option -c.
NOTE: If a download is stopped in middle, when you restart the download again without the option -c, wget will append .1 to the filename automatically as a file with the previous name already exist. If a file with .1 already exist, it will download the file with .2 at the end.