Many of us run two versions of Windows on the same computer using the dual boot mode. There are many benefits of having more than one version of Windows installed on your PC – it saves space on your desk (instead of two computer, you can use two version on a single computer), it is economical (you do not have to spend on extra hardware), it serves as a backup system (when one version of Windows stops running for any reason, you can switch to the other version and access all the files), it can help remove malware (if malware infects one version, you can boot into the other version of Windows and repair the whole PC using tools like ESET Online Scanner or any other regular antivirus scanner) among many others.
But when you re-install one version of Windows for some reason in a dual-boot system PC, it re-writes the boot entries for Windows and you can no longer boot into the other version. You are allowed to boot into just the one version of Windows that you have freshly re-installed. Fortunately, fixing this problem and going back into the dual boot mode is easier than you think. Here is a list of a couple of tools that you can use to fix dual boot settings:
1. Visual BCD Editor
This tool works on all the versions of Windows starting from XP to Windows 10. You will find different versions of this tool on its website that are suitable for different versions of Windows. In the Visual BCD Editor, you have to right-click on the Loaders and then choose which type of loader you want to add – Windows Vista/7/8.x, XP or Linux. After adding the appropriate loader, you can change its configuration settings (like the values for System Root, OSDevice and Application Device).
EasyBCD is an advanced tool and offers all kinds of BCD management but it is available only to work with .NET 4.0. So you must install .NET 4.x before you can start using this tool. There is no such problem with Visual BCD Editor which is available in different versions that an work with .NET 4.x or .NET 2.0. On the other hand, it is much easier to add a new entry using EasyBCD. To add a new entry using EasyBCD, you have to click on Add New Entry, select Windows, select the drive on which other version of Windows is installed and then click on the Add Entry button.
Using these tools, you can quickly and easily add the missing operating system entries back to your dual boot configuration without any hassles.