Deleted My Partitions by Mistake While Installing Windows 7

When installing Windows 7 on my computer, I accidentally deleted partitions on my 4 TB HDD. I can see some files on my HDD with TestDisk, but I failed to access the data in Windows File Explorer with a warning, 'You need to format the disk before using it.' How can I recover data from the HDD?

You cannot access the partition on HDD with TestDisk may because it has done an MBR conversion. Select "Reset GPT + MBR signatures" from the context menu when you right-click the first line, "Disk 2(Your HDD)". To see "GPT" on the first line rather than MBR, you might need to toggle GPT Off and On again. The NTFS partition should thereafter be able to be added at that point. If you cannot get what you want with TestDisk, you can try to use a partition recovery tool to recover lost partitions or recreate the partitions after recovering data.

EaseUS Data Recovery Wizard is a helpful tool to recover data from lost partitions on HDD. This tool will help you recover all files from your lost HDD partitions, including emails, documents, audio, videos, etc. No matter whether the data was lost on HDD, SSD, external hard drives, memory cards, or SD cards, this tool will help you recover the lost data.

1. The first thing after launching EaseUS Data Recovery Wizard is scanning the lost partitions. This step allowed users to scan the lost partitions quickly or deeply. Scanning a 4TB HDD will take a while.

2. You can select the files while scanning the HDD. If you want to recover photos only, you can choose "Pictures" from the Filter option.

3. Recovering files to another hard drive by clicking "Recover".

After recovering data from your HDD, you can follow the prompts to format your HDD to use it. In most cases, when a partition is destroyed or deleted, the system also deletes the hard disk assignment for that area, allowing the memory segment to be replaced as necessary. There is still a possibility to utilize the recovery tool to recover deleted partitions as long as this portion of the disk is unaltered. You'd better back up your HDD regularly with backup software or enable Windows File History to avoid data loss.