Before reinstalling, let's try something "less" destructive.
We're going to mess with the registry a bit so take precautions and have a backup handy, you can use Macrium Reflect for that (download to another PC and create bootable ISO media.)
Now, you will need a flash drive+a working computer with internet connection, or if you have the install disc around, that one. Find either the RE or the iso image for your OS (please be REALLY careful about os, edition, architecture, service pack and language matching, for example if you have Windows 7 Professional SP1 x64 English, you need to find the file with the same name). If you bought the Windows boxed, use the code to download directly from windows: https://www.microsoft.com/en-us/software-download/windows7 , if you didn't try to obtain an iso file as clean as possible.
Then burn that .iso file you downloaded to an USB drive. You can do that with Rufus, but I would recommend the Windows USB/DVD Download Tool (from Microsoft, weird enough it "downloads" the provided .iso file onto an USB drive, it's a simple writer: https://www.microsoft.com/en-us/download/windows-usb-dvd-download-tool)
Get the USB drive, it should be >4 GB and empty, because it will be formatted during the process, download and install the tool, run it, point it to the iso file, then the USB drive, and voila, you now have a bootable USB drive which we'll use to repair stuff.
Now your main objective is :
1)Determine if the problem is exclusive on the corrupt account
2)If 1 is true, activating the built-in admin account and working with it
Now you'll have to boot the corrupt computer from USB. In case you don't know how, https://www.acronis.com/en-us/articles/usb-boot/
You should see "Windows is copying files" or somethins similar to that on a black-and-white screen and you will be thrown to the win7 setup. (That's if you downloaded the whole disc, if you did RE skip here) Choose your language, keyboard etc, click "Next". You'll notice 2 buttons: "Install Now" and "Repair your computer", choose the repair option. You should be greeted with a few options. To activate the administrator account: https://www.wintips.org/how-to-enable-administrator-offline-in-registry-windows-10-8-7-vista/ Follow the steps carefully. You made a backup, didn't you? Close the command console and shutdown. Unplug the USB. Now, you should see another account named "Adminstrator" on the login screen. Use it to log in (I assume you can, if you cannot tell me) then follow these steps to create a new account, and copying your files to it: https://neosmart.net/wiki/corrupt-user-profile/