The trash directory is located at /home/username/.local/share/Trash .
Underneath that directory, "files" should contain any files you have deleted.
You can try opening nautilus, going to your home directory, and pressing Ctrl + H (The key combination for showing hidden files) and browsing to that path, or you can do it from a terminal.
Take your choice.
I hope that helps.
You can install trash-cli using "sudo apt-get install trash-cli" for a command line interface to manage your trash. It has a command restore-trash which should do what you are wanting.
EDIT2: Have you tried running "gksudo nautilus", and then going to trash via places, or pressing Ctrl + L and typing trash:/// ?
I have modified the python script that comes with trash-cli for the restore-trash utility to enable multiple restores. (Sorry didn't have enough time to do it from user input, but it will restore the first 10001 items in your trash) Open /usr/lib/python2.7/dist-packages/trashcli/trash.py in a text editor and navigate down to def run(self):
replace everything from (and including) that line down to def for_all_trashed_file_in_dir(self, action, dir): with the following:
trashed_files = 
if not trashed_files:
for i, trashedfile in enumerate(trashed_files):
self.println("%4d %s %s" % (i, trashedfile.deletion_date, trashedfile.path))
for item in index:
The next time you run restore-trash it will restore the first 10001 items in your trash.
Let me know if you have any problems, and I wish you the best of luck.