OK, I'm not sure where you got lost, but we'll go through this step by step. I'm going to start from the beginning so if you have already completed some of them just skip down to where you left off and go from there...You can do this!!!
First we are going to establish a temporary file in your C: drive containing the changes to machine.inf and a copy of two files needed to re-install the missing Plug and Play System Device Enumerator.
Copy the following:

Open Command Prompt>Start>Run>type cmd>OK...Right-Click near end of text and choose paste. Script will run.



Type exit and enter to close the command prompt
Temporary file should now be created. Should find it on your C: drive. Labled C:\temp. Looks something like this:

Open the Harware Wizard if it is closed.

Step1

Step2

Step 3 select Add Hardware Device

Step 4 select Install Hardware Manually from list

Step 5 select system devices (all devices)

Step 6 highlight standard system devices and press Have Disk

Step 7 Type C:\temp\ in box click Next

Step 8 Select Plug and Play System Device Enumerator from list on Right

Step 9 Installing Click Next

Step 10 Click Finish when Done
Plug and Play System Device Enumetator should now be in the Device Manager. If there are no conflicts with it or any of your sound drivers you should be good to go...