The following webpage suggests that it is possible to unignore files/folders with TortoiseSVN by right-clicking the file/folder and select "remove from ignore list". I do not have this option as shown below:
Also what is the difference between "Unversion add to ignore list" and "Unversion add to ignore list (recursive)"? I have read on here that "Unversion add to ignore list (recursive)" ignores all files/folders in the tree, but in my experience "Unversion add to ignore list" does this as well.
Right click on folder and go To properties. You will see list of all ignored files and externals.
Unversioned are the files which are either in source control nor in ignore