Can't access files on mounted vhd

I had a sudden hard drive crash and have a system image back up on an external drive.

I can't remove and replace the hard drive from the computer because there is about 2 inches of space to get a screwdriver in.

I plugged my external drive into a laptop and followed the procedure for attaching a .vhd file.

I have two files backed up on the same evening for some reason, 54 GB and 90GB.

I couldn't get the 90GB vhd to attach properly until I unchecked the read only tab, it mounted, but I couldn't access any files...

I clicked on the file, it asked me to click continue with admin control to permanently give access, it takes a few mins to load...but no files to open.

I really need some important files on that backup so how do I access them safely?

Thanks

Update, I tried some other folders on the attached vhd and I can access program files etc. The Users files where all the important stuff is empty...no files!

I have a sick feeling that windows has not been backing up the users/ my documents folders. Is that possible?