Changed the Disk to GPT Partition Style to Install Linux but Windows Can't Boot After That

I am having some trouble installing Windows or using it. I had an MBR partition and changed MBR to GPT using diskpart, but the Windows boot partition disappeared. If I tried using Windows installation USB, it gives the error that the disk is of GPT Partition style, which was on CSM boot, so I changed to UEFI boot, and it doesn't work. I hope there is a solution to this. I value any support.

From what you said, I learned that the Windows boot partition on your computer disappeared after changing the disk to GPT. Actually, you will delete all your partitions when you follow diskpart to convert the disk from MBR to GPT, including your original Windows Operating System. As a result, it still couldn't work even if you tried to change the boot mode from BIOS to UEFI.

In this case, you would better buy a new disk, recover the partition of the old disk on the new disk and reinstall the Windows system to it. And Use the old GPT disk to install the Linux. Follow the given step-by-step guide to fix your problem. 

1. Reinstall the Windows on the new disk

Buy a new disk and take the old one out. Then, you should connect the new disk to the computer to install and run the Windows system. The following link can lead you to complete the installation.

Further Reading: Fresh install Windows 10

2. Recover the deleted partitions

Boot Windows from the new disk and download EaseUS Partition Master, which can help you recover the data from the old disk using its partition recovery tool. Follow the tutorial to learn how to recover partitions:

After the above steps, the original data on the old disk should be restored to the new disk so that the new disk can work just as the old one.

3. Install the Linux on the old disk

To fully use your old disk, you can install Linux on it since Linux should be installed on the GPT disk. 

We sincerely hope this post can help you out.