Hi
Yes Ubuntu will let you access everything on your computer, and copy it to an external drive or disk, or another partition on you computer if you have one.
If you have an external drive I'd use that.
If you don't and live close to someplace you can buy one I'd get one.
They are very inexpensive now.
It will give you a place to store disk images and once you have your computer back up and running you can copy your files back to your computer and leave then on the external drive too.
I'm a fanatic, I have 4 of them, and at least 2 copies of everything, but I have files going back almost 20 years.
Once that's done you can chose Custom Install and it will install a whole new copy of Windows and remove all the old files.
It will probably save them in a folder names Windows Old, but you can't bet your files on it.
Once everything is up and running the folder can be deleted.
Personally I use ImageBurn to make the install disks from .ISO files.
Make sure that you get the same version of Windows that you have a serial number for.
And burn the disks at the slowest speed you can, less chance of errors.
Mike