Help! it won't install

I am downloading for origin for sims as i uninstalled but it won't install back into the computer, the downloading went fine and took a couple of minutes but it won't install, I've been trying for four days to install it. I've logged in and out origin, shut my computer down, repaired the game and uninstalled origin but nothing works. I uninstall the demo and reinstalled in a matter of minutes but the full won't do it. Help pls

This may help if you do a clean Boot
Windows 7 and Windows Vista

1. Log on to the computer by using an account that has administrator rights.
2. Click Start, type msconfig.exe in the Start Search box, and then press Enter to start the System Configuration utility.
   Note If you are prompted for an administrator password or for confirmation, you should type the password or provide confirmation.
   
3. On the General tab, click the Selective startup option, and then click to clear the Load startup items check box. (The Use Original Boot.ini check box is unavailable.)
   
4. On the Services tab, click to select the Hide all Microsoft services check box, and then click Disable all.
   Note This step lets Microsoft services continue to run. These services include Networking, Plug and Play, Event Logging, Error Reporting, and other services. If you disable these services, you may permanently delete all restore points. Do not do this if you want to use the System Restore utility together with existing restore points.
5. Click OK, and then click Restart.

If your using Window 8 i can copy and past for the Clean Boot

Before you do that clean boot. on Origin are you using your right account details i had same months ago and i was putting in wrong account user name?

When you go into your computer/Documents...is there a folder titled ELECTRONIC ARTS? If so, click on that, SIMS 4, should be the next folder... then what is inside there? Take a screenshot and show me.

You may have to clean your registry of the demo before you install the full version.