The "database" description you mentioned that you read about is a bit of an over-simplification.
chkdsk
will sometimes "convert" folders to files when the folder is too damaged to recover - it tries to recover as much as possible, it probably had no way of knowing it was a folder to begin with.
In any case, there is not really a direct way to recover those folders. Your main options are:
Restore data from a previous backup.
Make sure Explorer is set to show hidden files (I don't know how to do this in Windows 8.1 but in Windows 7 it's Tools -> Folder Options -> View -> Show Hidden Files / Folders) then look in the root directory of the drive for files and folders named "found.*"; chkdsk
will often move the contents of corrupt folders to directories here; and then you can put the files back where they belong. If all you have is .chk files some of the utilities below may help.
Try TestDisk - from the comments below, the OP was able to use this tool to recover missing files (the directory structure had to be rebuilt by hand).
Try some of the solutions from https://superuser.com/a/42205/245945 (I have never tried these and have no experience with them):
Replace lost data from its original source (e.g. reinstall damaged programs, etc.)
Try a file recovery tool such as Recuva.
If you don't have a backup, Recuva is your best bet of getting missing files back, although you may have to do some work to recreate the directory structure by hand. If you are going to try Recuva, then minimize the amount of data you write to the drive, starting immediately, because everything you write reduces the chance of being able to recover lost files.
Also how you recover data depends on the folders / files that were damaged. For example, if the lost data was program data from an installed program, you can reinstall it. If it was system data for Windows, perhaps running sfc /scannow
at a command prompt can repair it. If it was downloaded data, redownload it.
In the future, to prevent this:
Back up important data to a separate drive regularly. Programs such as Acronis True Image are great for this and well worth the reasonable price, and invest in an external drive like a WD MyBook or a networked drive such as the Seagate Central. There are many other options as well, depending on your level of knowledge and amount of motivation (I have a 4TB Seagate Central, it's compact and easy to set up, just plug it into your router and it will show up in Windows' network places).
Always shut down your computer properly. If power failures are a major problem where you live consider investing in a nice UPS, preferably one with the ability to communicate the power loss to your computer and allow it to shut itself down automatically.
Basically everything on this list, which you really should take a moment to read (note that backups are #1).