Vista - photos locked

I recently had to reinstall my operating system( vista home premium). I had
all my files backed up onto an external hard drive. I have got them back on
my C drive but some of my photos will not open. They are locked and a message
tells me to use the properties command in IE to unlock them. I played around
for three hours and thought I was getting somewhere changing permissions, but
I don't really know what I am doing. Many of them now open but after a while
they lock up again. Also some of the ones that open will not show thumbnails,
only a photoshop logo. I am signed on as an administrator and no-one ever
uses my password protected system except me. Any ideas?? Also I don't suppose
anyone knows how I can retrieve my windows messenger password from my hard
drive. My alternative email address is closed to me; I've forgotten the
password and the hint question and there doesn't appear to be anywhere to
ring or write to. I'm wondering if it is recoverable from my external drive
backup. Many thanks.Vampirelover.