Scanning?
I hate to appear dumb, or to make it seem that you are dumb, but are you sure you are talking about scanning?
Or are you talking about copying from a computer file and then pasting into Word?
With scanning, you put a piece of paper with typed text into a scanner, which makes a picture of the page, and then converts the text from an image to text by "optical character recognition" (OCR). If you are talking about this process, you simply have to know how to use the particular kind of scanning software that works with the scanner. It would be very difficult for someone to explain to you how to use a scanner without some more information, like the software that you are using for OCR, and then the person answering would have to know that particular software. I use OmniPage, and I have always found that it is confusing and cumbersome to convert a typed page to a Word file. I have done it and had pretty good (but not perfect) results. The formatting was always off a bit, but not gone entirely.
The reason I am not sure what you are talking about is that with scanning you normally get some kind of format. It could be, though, that your OCR software is set to convert to unformatted text. That is why I said that you have to know how to use your particular software, if in fact you are talking about scanning. (When you paste formatted text into Word, you often lose the formatting. If the original is in Rich Text Format, you may get something close to the original when you paste into Word, or you may not.)
Back to scanning ... My own limited experience with scanning pages of text is that I felt glad just to have text of any kind to work with instead of having to retype something. My software has an option to convert (through OCR) the image into Rich Text Format or Word. That seems to work haphazardly. I always have stuff to clean up, and each paragraph is in some kind of text box that I have to get rid of. I do not even remember the details (I try never to scan with OCR).
So, if you are really talking about scanning (which I think you are, now that I have reread your question several times), you might feel glad that you at least have editable text, even if it is all flush left. Reformatting is not that big a task. You do, however, need to know about paragraph styles in Word to make the reformatting painless.
For the record, though, scanning is great for making images for storage in a digital medium. You can scan photos or other documents and store them as images in computer files. It is great for keeping up with certain types of documents. However, the OCR feature (converting a page into text that you can edit) is a pain, and I rarely use it.