Hello! I am IT Miro and I will assist you on this question.
"File" is a general term used to identify anything that contains information. So, it can be used to identify your personal documents, pictures, music, text; but also, it can be used to identify a program's component. For example, Internet Explorer consists of many components (program files) which are needed for it to work properly.
Term "my files" can be interpreted as "my documents". Generally, all that you see on your computer can be divided into two main groups: files
Regarding Windows 8:
Yes, for a standard user that uses a desktop computer, it is not an ideal operating system. It makes more sense for tablet and touch screen users, since, in my opinion, the whole Windows 8 interface is adjusted to touch-screen. So far, Windows 7 is the best choice.
Too bad that the repair guy hadn't saved all your personal documents, pictures, etc (files) when installing Windows 7. Now is too late...
To avoid losing your personal files again, my recommendation is to create a backup of your personal files whenever you can. Use a removable USB drive to copy all important files there. That way, if something happens to your computer, your files are always accessible and mobile, so you can take that USB drive and connect it to another place, for example, at work.
Another solution is to upload your important files to the Internet so it can be accessible at all times, from almost any device. You can install a program named Dropbox
which will automatically upload (synchronize) all your files to the Internet. Click on these links below to learn how it works, then you can download and use it (it's free).Dropbox - VIDEODropbox - web site (download)
I hope this helps!
Let me know if you require further assistance.