How to Clean Registry Manualy

There are two hard options and one easy option.

Hard option #1:
-> Use the Windows RegEdit tool and manually go through every Registry entry.

Here's a screen shot of the Registry from a PC running Windows XP:



The Registry is organized in “Keys” (such as HKEY_CLASSES_ROOT). There are multiple levels of sub-Keys under each Key.

Clicking on the plus sign to the left of the Key shows the sub-Keys under that Key.
The number of sub-Keys varies from computer to computer since each Registry is unique to that computer.
This computer is about 3 months old. There are 6,089 sub-Keys under just the first Key. (And there are sub-Keys under those sub-Keys).

Then there's data in the sub-Keys. The data can be binary values, DWORD and QWORD values, string and multi-string and expandable string values, hexi-decimal values and ANSI characters.
Basically – not plain English. A daunting task to tackle manually.

A few keystrokes of mere mortal, human intervention could leave you with a computer that no longer boots up. And all your data unaccessible to you.

Hard option #2:
Step 1: Back up all your data.
Step 2: Find your copy of Windows.
Step 3: Find your copies of all the software and drivers you need.
Step 4: Reformat your hard drive and do a fresh install of Windows.
Step 5: Install all your software and drivers.
Step 6: Download all the updates and security patches.
Step 7: Copy all your data back on.
Step 8: Hope it all works.
(I left out the steps of groaning and cursing, I think you get the idea tho).