Ms word, excel, powerpoint and publisher cannot be opened after recovery

I have downgraded windows 8 to windows 7. Before the windows 7 was installed, my hard drive was cleaned so the 2 partitions become 1. I have created again 2 partitions and installed the os at drive c. I run recuva recovery software to retrieve the files I need. Unfortunately, MS Office files cannot be opened after the recovery and the files names were changed. Only mp3s, jpg, jpeg, avi, wmv mpeg are recovered fully. Are there ways to get back fully the MS Office files? Thanks in advance for your suggestions.