Replacing an HDD 3.5" USB 3.0 Enclosure in User to User Help Posted August 18, 2017 · Edited August 18, 2017 by terry1966 · Report reply ok. i didn't notice/realize it was a 3TB drive, which means it was formatted as a gpt drive, and because windows now sees it as a 2 TB drive i think it must be seen as formatted with mbr and not gpt partition table now. i've never used testdisk on a gpt drive so don't know what exactly caused this issue, at a guess i think it must be choosing the wrong partition table type to analyse it in the first place, i'm also not sure if we can still repair it now, especially as chkdsk made changes to the files by the looks of things, so all data is seen and usable exactly like it was in the old enclosure. the way i see it is you have 2 choices. first is to just use windows to delete the partition and then do a quick format of the drive as gpt so windows now see's it as a 3TB drive and simple use it. second is to continue using testdisk to analyse the drive but this time using efi gpt and not intel partition table and see if it can find and repair things. might even need to rebuild the bootsector again. you may need to run chldsk again when windows sees it as a 3TB drive with all your files and see if it will put things back to how they were before it made the changes it did when it saw the drive as 2TB, then again you may not if everything is seen and works. (you could try this second option even after doing the first.) But it was never actually partitioned in the first place, all drives are partitioned, they won't store data otherwise. you may not have partitioned it or formatted it yourself, but all drives need to be formatted and a single partition created before they can be used to store your data. think of it like this, a hard drive is a flatpack filing cabinet, useless until built. formatting is building the filing cabinet but it still doesn't have any draws to hold your paper work/data yet. partitioning is building the draws and inserting them into the filing cabinet. so now you have everything needed to store your paper work/data. good thing about a hard drive compared to a filing cabinet though, is you can easily change the layout and number of draws available to you at any time.