The drive was fine until the day it became a bootable installer — then most of its space 'disappeared'. It did not disappear. The bootable process redrew the map of the drive, and Windows only reads part of that map. Here is what actually happened to your 64 GB.
Every week, in repair shops and comment sections, the same confusion appears: a healthy drive goes in for bootable duty and comes back 'smaller'. The shrink feels like damage, so people reach for recovery tools and 'capacity restore' downloads. In truth the mechanism is simple, visible, and completely reversible — the partition map was replaced, and parts of the new map are written in formats Windows cannot read. Once you see the map, the fix stops being mysterious.
We imagine a pen drive as an empty bucket of 64 GB. The computer sees something else: a partition table — a map drawn at the very start of the drive that says where each partition begins and ends. Explorer only ever shows you the partitions on the map, never the raw drive. Anything not inside a partition is unallocated space: physically present, completely invisible. Every 'my drive shrank' story is really a 'my map got redrawn smaller' story.
Two kinds of bootable writing redraw the map. Image writers (the DD mode in tools like Rufus, and most Linux USB writers) copy an ISO image onto the drive sector by sector — including the image's own small partition table, sized for the image, not for your drive. A 4 GB or 14 GB image therefore turns any drive into a 4 GB or 14 GB drive on paper. Full installs — actually installing Linux onto the pen drive, as in the video — go further and build a proper multi-partition layout, just as they would on an internal disk.
A Linux install typically leaves three or more pieces: a small FAT32 boot (EFI) partition, the Linux system in ext4 format, and sometimes a swap partition — plus whatever space the installer did not use. Windows reads FAT32 happily, but it has no native support for ext4, so those partitions appear in Disk Management as anonymous healthy blocks with no letter, or are effectively invisible in Explorer. What you experience is simple: the drive 'became' the size of the one small partition Windows can open.
One popular tool is designed specifically not to do this. Ventoy installs its bootloader into a small EFI partition and leaves the rest of the drive as one large exFAT partition where you simply copy ISO files. A Ventoy drive therefore keeps almost its full capacity usable in Windows. If a drive shrunk anyway, some other tool wrote over it afterwards. The distinction matters when you choose a bootable method you will use repeatedly — the repeat-shrink page in this set covers that cycle.
Formatting works inside one partition — it empties and rebuilds that partition's file system and never touches the map around it. That is why a drive can be formatted a hundred times and stay 14 GB forever. Growing back requires redrawing the map itself: delete the small partitions and create one that spans the drive, which is what DiskPart's clean or Disk Management's delete-volume steps do. One honest exception, shown in the video: if the Capacity box in the Format dialog already shows the full size, the partition was full-size all along and a plain format finishes the job.
Watch the video to see the shrunken drive and the moment its real layout is revealed.
▶️ Watch Full VideoNo. Bootable tools change the partition table — the map — not the memory itself. Deleting the partitions and creating one full-size partition restores the drive completely, as many times as you like.
Because tools differ. Microsoft's Media Creation Tool lays out one partition across the whole drive, so nothing goes missing. The shrink appears with image writers that clone an ISO's own small partition table, and with full operating-system installs onto the drive, like the Linux install in the video.
That is exactly the pattern Ventoy is built for: a small boot partition plus one large data partition you can use normally in Windows. A classic image-written bootable drive does not offer that split — its leftover space stays unallocated and unusable until you redraw the map.