Can't see old time machine backups
Time machine can be problematic. A couple of things to try: 


open a folders that you can't access in finder, right click > get info, and check permissions. Does your user have read &amp; write permission?  
make sure your new HD disk name is the same as the old one.
try to access through time machine or finder.  
give it time - there are references in the apple forums of backups not being browsable right away, but eventually becoming available.