I Am Not Able to Convert Mbr to GPT, Need Help

I have a 500GB Toshiba HDD, and it is running on MBR, so I want to convert it into GPT because I hear GPT works fast and well. I open cmd and convert to GPT from diskpart, and it shows successfully converted. But when pc restarts, it shows no HDD or storage device is connected error (reboot and select proper boot device), and I check in bios my HDD is set up alone. When I turn off UEFI, Windows turns on. I check the properties and found that the disk is still MBR. Please help.

According to my experience, you failed to convert your disk from MBR to GPT for some reason, so the partition style of the system disk is still MBR. In this case, you only need to convert the disk from MBR to GPT again with the proper operation. However, before jumping into the conversion process for the second time, you need to run CHKDSK /F Command to check the hard drive to verify the file's integrity. CHKDSK stands for check disk and is a system tool that can scan your whole drive to find and repair the error. Find more details in the below article:

Related Article: Run CHKDSK /F /R/X Command to Fix Hard Drive Errors

If there is no integrity issue on the hard drive, you can begin to convert the HDD from MBR to GPT. You can still use Diskpart to complete the conversion. However, using cmd takes much time, and improper operation can cause errors, which leaves you to find better alternatives. To successfully convert MBR to GPT, I highly recommend you try the third-party converter tool, EaseUS Partition Master, it can meet all your requirements for the partition. With this handy and user-friendly tool, you can convert MBR to GPT with a few clicks. Although this software will help you convert the drive to GPT without losing data, it is always safe to back up your drive in advance.

This is a comprehensive tutorial on how to use EaseUS Partition Master:

Last but not least, configure the UEFI boot mode in the Boot Manager screen and enable the secure boot to protect your computer from malware.