I am wondering if you had used EFS (Encrypting File System) prior to re-installing windows. If so, your user account now has a new GUID, rendering your old files nearly useless. The files are still recoverable, but it’s not a simple process.
If this is not the case, might I suggest taking ownership of the files/folders. To do so, right click on the file/folder, click properties. Click on the security tab and then the advanced button near the bottom. From here you click on the owner tab and then take ownership of the file/folder. This may allow you to regain access to your documents. Hope this may be of some use to you.
Log in as administrator instead, try using windows explorer to access your files and adding yourself to the permissions on your files and folders.
Login with the account having Administrative rights. Try to take ownership on the My Documents Folder.
Please find the Microsoft Link for the procedure to take ownership.
I hope this will for you.
Thanks & Regards,