observe the hard disk, if it seem to have more files, it indicate more used memory than usual then you can recover files. please do nto format the disk, do not save anything, do not install many software.
solutions:
1.remove hard disk and read all yr info. put in external disk
2. install linux, obuntu operating system and read all your files.
3. just copy anything, even anything blank, even empty folders and put them in externalk hard disk. use another computer to read you pc.
4. scan you pc using an antivirus. which is good. i forget name but i will update u.
wish you good luck