Unable to launch Itunes

When I try to launch itunes, I get a blank window with "OK" in but no other message, I can click on the OK, but nothing happens and itunes doesn't launch! I have tried checking for updates, and I have also shut down and re-started. To no avail. Lastly I tried to open itunes in "safe mode" but nothing happened!

Can anyone help please??

many thanks in advance :-)