Windows Installer unaccessible and corrupted

[AndroidAssassin]

Been trying to solve a problem(s) I've been having for a while now: "The Windows Installer Service could not be accessed. [This can occur if you are running Windows in safe mode, or if the Windows Installer is not correctly installed. Contact your support personnel for assistance.]" and " 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.]" Both are practically the same, except one has a yellow "!"(which also mentions safe mode) and one a red "X". These are commonly reported problems in many forums on the web, but none of the solutions I have found can solve it. Those solutions being/involving:
- SFC /scannow (Returns "Windows Resource Protection could not start the repair service.")
- Unregistering and reregistering the service. (Does not display error but also does not fix problem.)
- Manually starting the Windows Installer Service. (Starts, does not fix problem.)
- Registry edit #1 from http://www.winhelponline.com/blog/misc-registry-fixes-for-windows-10-7-8-xp-vista/
Above 4 as suggested at http://www.tomshardware.com/forum/6828-63-windows-installer-correctly-installed-windows

- Manual Registry edit for key HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\SERVICES\MSIserver\WOW64 (No WOW64 under MSIserver.)
Above 1 as suggested at http://www.sevenforums.com/general-discussion/159447-windows-installer-simple-fix-worked-me.html

- I have also tried to create a bootable windows 7 usb, but I can not seem to get it working.
- My system recovery checkpoints were all deleted when this problem first occurred.
- May have tried and forgotten other methods, suggest anything that may work and I will try it.

I do not have a windows installation disk.
My specs are:
Windows 7 Home Premium 64-bit
Intel i7-4770k @4.2 Ghz
MSI z87-GD65 Gaming Motherboard
8 GB G.skill ripsaw memory
850w Corsair Professional PSU
2 R9 280x in crossfire

Hopefully one of you geniuses can help me. Will update with solution if not in thread.

 

[penguintech]

First download a legit copy of windows 7 from here:
https://www.microsoft.com/en-us/software-download/windows7
follow the steps to get your download.

To create a bootable Win7 USB from the above download you will need to use this:
http://wudt.codeplex.com/ ( link provided by Microsoft )

You can then try this:
backup the reg first of course, then from “HKEY_lOCAL_MACHINE/SYSTEM/CurrentControlSet/services/msiserver” just remove it completely. Replace with one from a different / functional PC, reboot and maybe a quick sfc /scannow , you might need the windows 7 disk for this step.

If that doesn't work try the MS provided "Fixit" here
https://support.microsoft.com/en-us/help/17588/fix-problems-that-block-programs-from-being-installed-or-removed