Win 7 computer won't stop reformatting/ restoring.

I'm trying to reformat my mother's Win 7 computer. I have never done this without the old disk method. I believe what she started with was restoring it to factory settings, and it seemed to work well. When it finally finished though, it said that there was an error and started all over again. Now that is all it does. It goes through the process of reformatting, and when it is done it reports an error and starts over again. I have no idea what to do and can't find any information on this happening. The reason that we decided to reformat in the beginning was that she was experiencing severe lag when using the internet (without any internet service or connection problems) and could not get rid of a Chrome issue where it would continue to generate ads whenever she did anything (not sure if it was a virus, malware, ad-ware, etc.). Any information on what should be done or possible fixes would be greatly appreciated. Thank you in advance for your time.

Thank you for the help.

I'm really confused by this, because we didn't get an installation disk. I know we used to get them. Now we just get computers. I'm not sure how to make one. I'm sorry I'm so confused with this.

Thank you so much! I really appreciate the help.

I cannot find a site that has a working link to download 64bit Win 7 for home. The link provided goes to a 404 page, and so does every other page I've found that has the file. I even tried on another page, asking for links, and I was only given dead links. Does anyone know where I can get a working link to make this disk? At this rate, I'm never going to get this computer working. I have to share mine until I do...