How can I decrypt my Windows 7 files?

I had Windows 7 and encrypted some of my files and folders. My windows 7 ended up failing so I made another partition on my hard drive so I can access all of my files from the other partition. It works but now I cant open my encrypted files or folders. Every time i try to, it says you don't have permission... and if I try to add my computer to its allowed list it says can't find certificate. so how can i decrypt and access these files? please help it is very important!