Windows Installer Service could not be accessed

Question

Whenever I try to install a program I get the following error:

The Windows Installer Service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance.

I am running Windows 7 Ultimate - Version 6.1 (Build 7600).

I have tried the following solutions, to no avail:

1. Go to services.msc and start Windows Installer
   When I try that, I get the error message:

   Windows could not start the Windows Installer Service on Local computer. Error 5: Access is denied.

   When I tried as Admin, I could not even open services.msc. It said:

   This function is not supported on this system.

2. Deleting a second msiexec.

   When I went to C:\Windows\system32, there was no second msiexec.

3. Modify Remote Procedure Call Service

   When I got to the Log On tab I was not able to choose Local System Account.

4. Reinstall Windows Installer Service by downloading MSIServer

   After I merged the two files nothing changed.

5. Install the latest Windows Installer version.

   I already have the latest version.

6. Run regedit. Navigate through HKEY_LOCAL_MACHINE…SYSTEM…CURRENTCONTROLSET…SERVICES…MSIServer. Then right click on WOW64 and select “Modify.”

   When I got through the steps, there was no WOW64 for me to choose.

I do not know what else to try.