How to recover my encrypted files

[suveduka]

Hai everybody,
Can anyone help me. The problem is this. I am having windows xp prof sp2. Two months ago I encrypted 20 files. In that time my administrator name was sundaramurthy. In between I formatted the C drive and installed the same OS but with administrator name sundaramoorthy. Now I cannot decrypt the files which I encrypted before installation. In that file details it shows that sundaramurthy is the owner. When I try to add the present administrators certificate, it displays Error in adding user EFSADU. Please any one help me to solve the problem.